Grooveshark, the music-streaming app that's had a home on Cydia for the past year, was kicked out of the App Store after Apple notified the company that they received a complaint from Universal Music Group UK.
While Apple has approved streaming music apps (such as Rhapsody) in the past, Grooveshark's woes appear to be related to a lawsuit between the company and Universal Music Group. The lawsuit, reported by CNET in January, alleges that Grooveshark is distributing illegal copies of the company's music. A similar suit with EMG was resolved in 2009.
Grooveshark is still available for other mobile devices, so if you're a fan of the service, you may want to stick with your Cydia copy if your iPhone is jailbroken or download it to one of those. I don't think we'll be seeing this app back in the App Store until this lawsuit is resolved.