Ello, the ad-free, idealistic social network that captured our imagination when it launched in the fall before receding into the background, is ready for its second act. We called Ello "half-formed" when we looked at it last year, with one of its most glaring omissions being the lack of a smartphone app in a world gone mobile. That's being corrected today as Ello launches its iOS app (Android and Windows Phone are planned for the coming months).

Ello co-founder and CEO Paul Budnitz made it clear that he feels like this app release marks a more formal, feature-complete launch of the service, compared to what came last fall. Users can now join without an invite, and he thinks the platform is now ready for public consumption beyond those who invited their friends previously. "The only thing you could do [on Ello at launch] was post and follow people," says Budnitz. "The reality is that we wanted to make sure that all of the features of Ello were really solid before we got to mobile." Those features now include commenting on posts, the ability to repost and "love" content, and the ability to post large images, videos, and sound files from Soundcloud — Ello feels a lot more like Tumblr now than the bare-bones, text-only experience it started out as.

The entire core Ello experience is intact on the iPhone, just as those who've used the service would expect. It retains the stark, minimalist black text on white background look, but there are a few notable features on board here. Unsurprisingly, Ello is making it easy to discover interesting users — either your own friends or people already actively contributing to the Ello community. For the first time, there's an option to have Ello scan your phone's contact list and find people who are already on the service — "kind of an important feature for a social network," Budnitz said wryly when telling me about it. That feature is found on the "discover" tab, which Budnitz tells me is a mix of hand-curated users as well as algorithms that find you posts based on who you already follow.

Unsurprisingly, Budnitz stressed user privacy and anonymity in how it implemented the "find your friends" feature — the email addresses in your contact list are encrypted and sent to Ello, where they're compared against encrypted email addresses on the server. He compared it to a "lock and key" situation in which they have to "fit together perfectly to be a match," at which point results are returned to you. "We can't reverse engineer your address book," he says, "it's useless data to us that gets thrown out."

Budnitz was also candid about Ello's future — including monetization. He said that he expects the launch of the Ello app will start driving a corresponding increase in active users, and the company's first step towards making money from those users will be allowing them to sell things right in their feed. While Ello has no plans to introduce ads, a user or brand will be able to post things in their stream that other users can click on and buy — Budnitz likened it to Etsy or eBay, with Ello taking a small cut of the sale. You won't start seeing "for sale" posts in your stream unless they are from people you've already decided to follow, and if you don't want to see commerce-related posts you can simply stop following that person.

The company is also planning to launch direct messaging and group messaging features before its commerce platform starts rolling out. But in the case of all of these features, the question is: who will be using them? I tried the new "find my friends" feature with Ello and discovered that no one I know is using the service regularly. That's not necessarily a deal-breaker, as crazy as that might sound — I also don't know too many people on Tumblr personally, but the site can still be a treasure trove of interesting material. If Ello can manage to get more creative people posting interesting things on a regular basis, it has a chance to be more than the doomed utopia it currently is. With mobile being the way most people interact with social networks, releasing good smartphone apps is one of the most important things Ello can do to find a place in the world.