I am slowly extending my base of used operating systems: after Windows and Solaris, I am now playing a bit with Ubuntu. This is quite exciting for me, since after about 8 years of the early days of Linux (I started with SLS, kernel 0.99.7) I started to focus more on Solaris and Windows after joining Sun. A lot has happened since, and I am quite pleased with the end-user experience that a modern distribution like Ubuntu offers in these days.
One issue I had (like Lauren) was that hibernation of Ubuntu 7.10 was not exactly working out of the box:
Sending the system (a Toshiba Tecra M2 with a GeForce FX Go5200) to hibernate was very straightforward. But resurrecting it after a hibernation resulted in a dark screen. I tried a couple of tricks I found (like using the extremely useful toshset(1) utility, part of the Gutsy Gibbon distribution), but to no avail.
Finally, I stumbled over a setting to be applied to the X configuration (see also here). It requires disabling the chipset AGP drivers (e.g. intel_agp) and enabling the restricted NVidia driver to provide AGP support by setting a separate option in the xorg.conf file.
Now, hibernation and wake-up work with one little caveat: after waking up the system, you must close the lid for about 5 seconds, in order to have the backlight turn on.
 Note that I am using the NVidia proprietary drivers.