With the large pile of laptops I've tested, one thing that was pretty clear was that suspend on laptops with nVidia graphics hardware is a bit less reliable than anywhere else. At first, I thought that it was just a lack of quirks in hal for the machines in question as they didn't have any. But with some more looking, it's looking more and more like there are bigger problems and that we either don't have the right infrastructure to quirk it or (more likely), there's a need for some work within the X driver and/or the kernel to properly poke the chip into working again post-suspend. Given that time for that is rapidly dwindling and I'd rather not have people try to suspend and have it fail, I'm building a pm-utils that will (by default) show that suspend isn't supported on machines with nVidia graphics using the nv driver. You can override this by creating a file in /etc/pm/config.d that contains a line
While not ideal, hibernate works and this way at least the unsuspecting user doesn't hit the problem. A better fix for this is likely to need to come either from nVidia within the nv driver or from the work being done on the nouveau project.