Unfortunately, I didn't find any satisfying editing tool for my HD videos under Ubuntu -- Kino is a good tool, but it's not HD ready. There are some others, but none reaching the stability and features of say, Pinnacle Studio under Windows.
I'd love to be proven wrong. However, for the time being I'll keep a XP partition for video editing.
P.S. for very small editing tasks, avidemux does the job well.