We’ve written about Zeebox before: co-founded by former EMI exec Ernesto Schmitt and former Kazaa-er Anthony Rose, its ‘second-screen’ app is part social TV guide, part Twitter-curation tool for TV viewers. It launched in the UK last year, and now has around 350k active users, but today it goes live in the US too – complete with investment from Comcast Cable and NBC Universal. Zeebox will be competing with US apps like Miso, GetGlue and IntoNow, as well as another company that’s familiar to the music industry: Shazam. “It’s the next stage of this second screen space – the moment that second screen grows up,” Rose tells PaidContent. The music angle here is that Zeebox’s features include providing iTunes Store links for music played on TV show soundtracks, which now it’s in the US could make it an increasingly significant driver of sales on Apple’s store.