The long-awaited iPhone app for Turntable.fm, this summer's hottest group listening service, is now live in the iTunes App Store.

The service, which lets people play music for eachother's animated avatars in virtual rooms, is sort of like a virtual DJ night broken down by genre. People take turns playing tracks and other users can cast their vote for songs as being "lame" or "awesome" and chat with each other in real time. If the desktop experience seemed cool, the service feels even more at home on the iPhone.

This is the service's first official foray into the mobile space. Until now, it has only been available via dekstop Web browsers. That may make for a fun way to stream a group-curated music playlist at work, but having it available on mobile devices takes things to a whole new level.

The app's developers managed to port most of the Web app's critical functionality over to the iPhone, including the ability to create rooms and add songs to the queue.

Just like on the desktop, Turnable on the iPhone can be a hands-on, interactive experience or a lean-back and listen kind of experience. You can play music and interact with others in the room, or you can mimize the app and just listen. In that sense, the app can be used similarly to Pandora, but with entirely human-powered playlists.

The app was designed primarily for iPhone, but we downloaded it onto our iPad and the interface actually translates quite nicely to the larger tablet screen. Whereas some iPhone apps can appear grossly pixelated on the iPad, the distortion on this one is minimal.

They even added a few nice touches to the UI just for iPhone users. For example, if you start a DJ room from the iPhone app, your avatar will be shown at the front of the room holding up an iPhone, as opposed to sitting behind a laptop, as the other avatars are.

Turntable.fm was created by Stickybits, a company that initially produced a mobile app by the same name that lets you scan barcodes to unlock related deals and social interactions. The Stickybits team turned their attention to the group listening space earlier this year, launching Turntable.fm in private beta in June. The service quickly became one of the hottest music apps of the summer, spawning several copycats and much love from the tech press.