It's named SingStar and it features BritneySpears and many other singers! The way you play it, is by competiting with your friend or family member in singing a song from who ever you like.
"Take centre stage and wow the crowd with your performance as SingStar arrives on PlayStation 3. For the first time ever SingStar lets you personalise your playlists by downloading the songs of your choice -- so you can sing along to what you want, when you want it.
Customise your SingStar experience by downloading the latest tracks and menu skins from the SingStore (an in-game shop accessible directly in-game, with the entire SingStar back catalogue of songs as well as new tracks.)
Set the world alight by uploading your best performances to the online SingStar community and go wild with superstar moves with the exclusive new silver microphones.
Share your performances as you instantly upload photos and videos captured via the EyeToy camera, taking the best bits on the go on your PSP -- so you can be a star wherever you are."