Lots of not-quite-confirmed stories are claiming that 'I Wanna Go' will be the next single from Britney's 'Femme Fatale' album.
The announcement initially came from Britney fansite Breathe Heavy, and has been reported on numerous other sites, although MTV News noted that Britney's 'rep' hadn't responded to a request for confirmation.
The closest to an official announcement so far comes from 'I Wanna Go' co-writer Savan Kotecha, who tweeted:
[blackbirdpie url="https://twitter.com/#!/Savan_Kotecha/status/68292652587696128"]We're still waiting for Britney's 'people' to confirm it, though.