I installed the uswsusp package, and now hibernate works again.
SIDE NOTE: Before installing uswsusp, I also made a few other changes, which didn't seem to help. Here are the changes I made, just in case they had anything to do with the resolution of this issue.
I edited /etc/default/acpi-support and set MODULES="b43 ssb"I edited /etc/default/grub and appended SUSPEND_MODULES=\"b43 ssb\" to GRUB_CMDLINE_LINUX_DEFAULT
