If you've had your head buried in the sand (it's gotten a lot of good press), you might not have heard about Boxee. Boxee is a project based on the xbmc (XBox Media Center) open-source project. Boxee was developed to be a “social” media center program that plays media from your home network and the internet and also allows you to stream or download movies, tv shows, music and photos.
Starting January 8, 2009, Boxee will move from alpha to beta meaning all Mac and Ubuntu users that want to try out the Boxee Beta will get their chance (it was limited to a smaller group of alpha users in the past). If you haven't signed up already, head over to Boxee and do it now.
For the Windows users, the windows version is still in alpha so it's still closed to a smaller group, but the CEO commented in the Boxee post that the Windows alpha program will begin in "early 2009" with plenty of invites to go out each week.
One more thing - if you are interested in joining the limited number of early-access users for the pre-release boxee versions, head over to Boxee and complete this form to see if you can get on the list. via Boxee Blog