Pandora Radio, the personalized internet radio service that has remained among the most popular iPhone apps on the iTunes App Store since its inception in July (and that I’ve previously called the iPhone’s killer app), will be releasing its most significant update yet later today.

Dubbed Pandora 2.0, the application will now include artist biographies, streaming samples for songs you’ve bookmarked, and perhaps most notably, the ability to create a station using a single song (much as you would using the iTunes Genius features). Other features in the new release include a CoverFlow-like view for song history, the ability to share stations with friends using Email, and a song progress bar (which has long been annoyingly absent).

Pandora has been around for years, offering a very powerful music recommendation engine powered by The Music Genome, which employees professional musicians to describe each song using over 150 attribute (or “genes”). Its iPhone app closed out 2008 ranked as iTunes’ top free application overall, and it doesn’t show any signs of slowing down.

Update: It looks like you can download the application now here. The application page still shows the older version, but you’ll download the 2.0 version of the app.