I held off updating Kubuntu for the past couple of weeks. I was debating about moving to Jaunty Jackalope, but I decided to put that off too, but today I figured there was no point in not doing the regular update. I did notice that it included a new kernel, which always caused me problems in Fedora, but so far hasn't affected me in Kubuntu.
Well, I did have a problem. I don't think it was kernel related though.
This may have been my first update problem with Kubuntu. Firefox wouldn't start. When I tried to run it from the command line, I got the message Could not find compatible GRE between version 1.9.0.1 and 1.9.0.*. I was able to Google the answer using Konqueror--http://kubuntuforums.net/forums/index.php?topic=3097864. Heh, up until now I didn't know there was a separate forum for Kubuntu. The solution was at the bottom: sudo xulrunner-1.9 --register-global