Couple of times I wanted to use Boxee in Ubuntu 64 bit, but failed attempting it because there was no official support for it. Recently I found that they have released it Ubuntu 64 – Boxee. I downloaded and installed the .deb file and it started and worked without any problems. Even IR remote which I had configured for XBMC worked without any change for Boxee too, which I believe is because Boxee is based on XBMC code base.
Also I fount that they are planning to sell a hardware Boxee Box, which looks good, but one more addition they can make to the hardware is to add a DVD / Blu ray drive