Well, I'm not entirely sure what happened, but my Ubuntu partition is hosed. If I try to do a standard boot, I'm stuck with a blank monitor after the Grub menu. Selecting "Recovery Mode" shows me the following:

run-init:  /sbin/init:  No such file or directory
Kernel panic - not syncying:  Attempted to kill init!
Pid:  1, comm:  run-init Not tainted 3.2.0-34-generic #53-Ubuntu
The stack trace follows that, and the system hangs.

My first thought was that the filesystem got corrupted somehow (maybe an update or a nasty reboot), so I booted to my my flash drive (Ubuntu Live CD). Following a few other similar threads online, I ran:

sudo debugfs
crli <8>
Followed by this:

sudo fsck -yv /dev/sda1
fsck found a _bunch_ of errors and fixed them, but I still get stuck with the same error when I try to boot...