The strange thing is that (after using pmdisk= instead of resume= :p), it resumes well and puts the swap back in its original shape (at least, it's a swap afterwards)
I have a few problems with resume though: - the fb console is often totally messy. Very big and ugly lines (something like 4 lines on the screen), some lines are overlapping with other ones. It is fixed when X comes up. - sometimes the X window is yellowish after resume. I do go on a VT before suspend. - .Xauthority seems to be modified in the process, but since I'm using the (slightly modified) hibernate script from swsusp2, I'll have to check that it does not come from it (does not seem to be that, though). I'm using an ibook G4/800/12"