Well, I know this is tempting fate, but I’ve got 48:03 on the uptime monitor, so perhaps the recent Karmic xserver updates I’ve recently installed have sorted out the X freezes (see here, here and here). If so, I am mighty relieved, as this was a bit of a show-stopper for me.
Update: now 61h14m, but sometimes it logs me out when I resume from suspend. Guess that’s a risk one takes when one is using the alpha version of Ubuntu GNU/Linux 9.10?
Update 2: the blasted notebook froze just as soon as I saved the above edit! Rats!