After making some changes to my swap space, namely deleting and recreating swap space, my Kubuntu 11.10 has lost hibernate functionality. Although the button has returned, hibernating only appears to be working superficially until you try to resume the system - but instead of resuming you find it is restarting.
Filename Type Size Used Priority /dev/sda5 partition 10237948 0 -1
# /etc/fstab: static file system information. # # Use 'blkid -o value -s UUID' to print the universally unique identifier # for a device; this may be used with UUID= as a more robust way to name # devices that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosuid 0 0 # / was on /dev/sda3 during installation UUID=0b109499-4feb-4ec1-b368-c7f945194e44 / ext4 errors=remount-ro 0 1 # swap was on /dev/sda5 during installation #/dev/sda5 none swap sw 0 0 /dev/sda5 none swap sw 0 0 /dev/fd0 /media/floppy0 auto rw,user,noauto,exec,utf8 0 0