First off Kdenlive is great. Keep it up! I'm beginning to use Kdenlive as my primary NLE for production.
I do want to suggest, however, that Kdenlive get better audio and video thumbnail ability. It seems to take too long to create the thumbnails, especially when I import multiple clips at once. In other editing programs, even Cinelerra in linux, the thumbnails appear very quickly/instantly. Also, I've experienced Kdenlive recreating thumbnails for clips I know it already has thumbnails for when re-opening a project.
Also, the thumbnails should scale with the size of the track (height) size. When you expand the tracks the thumbnails don't fill the space - maybe there's a reason for that...
THe audio waveforms in the audio thumbnails are not very useful when trying to align clips via the audio. The audio thumbnails should look like those in Audacity, especially when zoomed in really far. The way it is now is almost useless (or I don't see the advantage) because you cannot distinguish different waveforms. (What' up with the things that look like triangles when zoomed in on the audio?).
Video thumbnails should be shown along the entire track so it is easy to know what is being shown in different parts of clips without having to move the timeline cursor.
Anyway, to summarize, here's what I hope will be in Kdenlive's near future:
1. Faster and more reliable thumbnail generation
2. Audio and video thumbnails should scale with the track height
3. Better audio waveform representation in audio thumbnails - these should look like and be as clear as waveforms seen in Audacity.
4. Video thumbnails should show along the entire length of the clip (see Cinelerra for example).
Currently, I'm using 0.7.9.