Boxee announced today from CES that it has added Joost and the BBC iPlayer to the litany of video services that run on its open source media center. The company also announced that it is opening up its alpha to all Mac, Ubuntu and Apple TV users and that the Windows version is moving into private alpha (but it sounds like everyone who asks will get an invite).

Sorry, BBC fans living in the U.S., the iPlayer will only be accessible from inside the UK (bummer, but to be expected). Joost, on the other hand, will work here, and you’ll get access to all of the content in Joost’s library. In addition to these new content partners, Boxee also expanded its MTV Music offerings, allowing users to search for songs inside the MTV app, or just browse through its music catalog.

Boxee, which launched its alpha last June, landed $4 million in venture funding in November and integrated Netflix streaming in December, also said today that more than 200,000 people have signed up for the service.