RIM has just unveiled the latest iteration of the BlackBerry 10 operating system, set to be released on new devices early next year. We have finally gotten a look at the UI RIM will be shipping, and it's an interesting mix of user interaction metaphors we've seen on multiple devices to this point and a strong progression from the version of the software we first saw back in May.

We have separate a hands-on post with the Dev Alpha B hardware, but what you should know is that it's a simple black slab, a boxy, full-touch device that RIM said it had to make simply because it ran out of units of the original Dev Alpha. We strongly suspect something that RIM isn't saying: it looks likely that this is an alternate, boxy version of the L-Series "London" phone that will be its first BlackBerry 10 device.

The device is running the "Beta 3 SDK" of BlackBerry 10, which has the look and feel that consumers can expect on the actual phones the company is launching next year. RIM has been talking about the "flow" of its next OS, and there are elements here that are genuinely interesting.

As you swipe up, the lockscreen fades under your finger

Starting with the device in sleep, you can wake it simply by swiping up from the bottom of the screen — no need to hit a power button. As you swipe up, the lockscreen fades under your finger to reveal the OS underneath in a way not entirely dissimilar from what LG has done on its recent homescreens. The lock screen also shows how many (and what type) of notifications you've missed and allows users to launch the camera directly.

Once you're in, the OS starts with a multi-paned home screen. The first screen holds up to 8 "Active Frames," which are the applications currently running on the phone. The Active Frames are listed in reverse-chronological order, with the most recent at the top left. You close apps by tapping a small "X" in the lower-righthand corner (or, presumably, by opening up a 9th app). Four of them will fit on a single screen, and you scroll down to get the other four.

RIM was careful to point out that these are not widgets or live tiles, but the actual running applications displayed in thumbnail form. Normally this will just be a shrunken-down view, but if an app supports it, it can display an alternate view in this reduced size. As with the PlayBook, the running apps are always running, so there's little-to-no wait time to launch them from this screen.

These are not widgets or live tiles, but the actual running applications displayed in thumbnail form

To the right of the Active Frames homescreen is a standard grid of icons. They arranged manually like they are on the iPhone, including support for drag-and-drop folder creation. As we've seen on leaked screenshots, this grid of icons is decidedly square — both the folders and the apps themselves live in small rectangles.

Switching between apps involves a swipe-up from the bottom of the screen, which takes you back to the homescreen where you can select another app. RIM actually removed all of the side-gestures it had in the last version of this OS, so there's no way to switch directly between most apps. Swiping down from the top bring up settings and other menu options, depending on context. In all, it's a user interface that's a mix of Windows Phone, webOS, and iPhone — but there's one major exception, and that's the "BlackBerry Hub."

The BlackBerry Hub is the RIM's unified messaging solution that integrates all of your email accounts, Twitter messages, Facebook messages, and LinkedIn messages. It also serves as a unified notification center — third party developers will be able to send notifications the hub, though full messaging integration won't be available to them at launch. Within the hub, there's a universal inbox that collates everything or you can filter to each individual email account or service (though you can't create groups of, say, your personal email and Facebook messaging).

The Hub sits to the right of the Active Frames homescreen — and indeed, the right of every screen. You can access it directly from anywhere by making an upside-down L-shaped gesture from the bottom of the screen. That is, you swipe up and to the right to "pull" the hub out from underneath any spot in the OS. You can just "peek" by making a partial gesture, if you just want a quick look at what's setting off the LED indicator.

Although describing the gestures to bring up the Hub is a little complicated, in practice it's fairly intuitive once you've done it once or twice. It's also less likely to come up accidentally than what we saw in the last BlackBerry 10 Beta, where it sat on the right of every screen and was brought up with a swipe from the side of the screen.

BlackBerry Balance looks unintuitive, but most consumers will never use it

For better or worse, no discussion of BlackBerry would be complete without seeing how it will operate in a corporate setting. In BlackBerry 10, RIM is extending functionality it calls "BlackBerry Balance," which allows locked-down enterprise functionality to co-exist with personal apps. Enabling it is unintuitive: you pull down on any blank spot in the app launcher to reveal a couple of buttons. Tapping one will put the phone into either work or personal mode, and when you launch an app that will be either locked down or fully open, depending on your company policies. RIM will also allow companies to make company-specific App World "stores."

When you launch an app in "Work" mode, its Active Frame has a small briefcase icon on it to denote that it's running in a secured mode. If you company won't let you copy and paste from the browser, for example, you won't be able to do it in that secured app — but you can launch a "personal" browser instance alongside it.

Like the "peek" gesture for the BlackBerry Hub, it's a little confusing at first but makes sense as you use it more. It's a reasonable solution for the hassles of straddling both the locked-down corporate world and the more-open consumer world, but it can get messy. For example, RIM says that some apps, like the BlackBerry Hub, run in a "Hybrid mode" that combines both personal and work functions. RIM's perennial problem has been finding a way to appeal to consumers while still satisfying the security and management concerns of corporate IT — and that applies just as much to BlackBerry 10 as it did to previous iterations. Most consumers will never use it, and that seems like a good thing.

What about actually using BlackBerry 10? It's actually not bad at all — it's as fast at re-opening running apps as any OS we've seen and having messaging always be one swipe away is quite convenient. Our short experience with it felt like living in a strange middle ground between the iPhone's icon-based UI and Windows Phone's live tiles. If you're mostly using 8 or fewer apps on a regular basis (and you don't have to count messaging apps, those are "free" in the hub), we could see this being very efficient. That depends, of course, on whether there enough flagship apps to work with, something RIM is doing its best to make happen.

That's the current state of BlackBerry 10, but is it final? Probably not: RIM promised that there were still a few "surprises" in store. We still haven't seen the company's full strategy for music, movies, and TV, for example. RIM also says that the Beta 3 is very close to being "API Complete," saying that all of the developer hooks that are currently in there are stable and will launch — but there still may be a few more that could become available.

RIM has a very difficult road to travel with BlackBerry 10

RIM has a very difficult road to travel with BlackBerry 10: it needs to get a critical mass of apps by launch to even get a first look from consumers, let alone a second one. To prepare developers, the company has had to keep them up to speed by trickling out information about the next platform instead of unveiling it all at once with a big splash. That has made for a series of teases and hints, but not a complete picture of RIM's mobile strategy.

Time will tell whether this strategy of slowing revealing details instead of making a single, big announcement is the right move. If RIM is right, it will help boost the app ecosystem in time for launch without detracting from the excitement a single launch could have garnered. If RIM is wrong, by the time BlackBerry 10 devices ship, they might feel old hat.