The audio and video is out of sync if the video is cut in kdenlive version 0.7.7.1 on Ubuntu 9.10 64bit. You can work around this by using "Split Audio" then "Ungroup Clips" and moving the audio to the correct spot. I usually move the audio forward either a half a second or a full second. You can also not fast forward, or the audio will be more out of sync then it will be in the rendered file.
You can also work around the problem by exporting the full video with no cuts, then adding the rendered video to your project.