At this time, RockMelt is only compatible with Intel Macs OS X 10. 5 or higher, Windows Xp, Vista, or Windows 7. For all other platforms (including Linux / Ubuntu), we have no date set for a release but we hope to be able to have one in the near future. The reason we can't just port RockMelt over to Linux is because a lot of our code is native to the operating system.