Boxee is basically an open source media center application based on another critically acclaimed open source media center application called XBMC. I have been using Boxee since its early alpha releases in my Ubuntu and its been a wonderful journey. Boxee is incredibly stable and its ever growing number of apps is proving to be the real difference.
An application to easily browse and watch TED videos is my favorite application among hundreds of similar Boxee apps. Boxee recently added support for Live News also which pretty much nullifies the need of a regular TV. You will also find instructions for installing Boxee in Ubuntu in the same link as above.
People who pre-ordered from Amazon should receive their Box as early as Nov 11. And the Boxes should start appearing in stores on Nov 17th. You can also pre-order Boxee Box from Amazon right now. More info at Boxee Blog.