It's old news by now that when Apple releases a new iPad, it also releases a new version of iOS. This time it's 5.1, and while it might not be much to look at this time, it's still a pretty useful update. Japanese language support for Siri is a nice addition, as is the new lock-screen camera button — instead of requiring a double-tap on the home button, it's always present whenever you turn on your iPhone, and you swipe the lock screen upwards to reveal the camera app. It's a neat animation, and makes getting to the camera even faster. Apple also redesigned the camera app on the iPad, and it's even more bare and simplistic than ever; paired with the huge hardware upgrade in the new iPad's camera and the new iPhoto app, it should make the iPad a pretty formidable tablet camera.
Most of the other changes in 5.1 are just bugfixes: you can now delete a photo from your Photo Stream, for instance, a feature it's hard to believe wasn't already present. You can also create Genius Mixes and Genius playlists using your iTunes Match information, and there have been a few enhancements to audio and call quality. There's also an "updated AT&T network indicator," which seems to be nothing more than adding a "4G" icon to the top bar of the iPhone. It also, apparently, leads your iPhone to tell you that you now have 4G coverage where it used to have 3G. The update doesn't seem to have a measurable impact on the iPad's performance, though a couple of Verge staffers swear their first-gen iPads are faster now.
You can install iOS 5.1 now, as long as you have a recent version of iPad, iPhone, or iPod touch.