/dev/sd* disappeared from userspace

[Todd Pytel <tppytel@sophrosune.org>]

I recently began updating my desktop, a Sid install which I only update
infrequently - the last update was a few months ago. As I usually do in
this situation, I started by pulling down the various non-X/GNOME
libraries and basic admin, devel, and text tools. Before too long, I did
a reboot to test the GRUB 2 upgrade, and noticed that /dev/sda - my
system disk - is no longer listed in /dev. Oops. 

I can basically boot up, presumably because the pointers in GRUB get the
kernel to the root fs and init, but once running the disk is no longer
visible. It's detected by the kernel in dmesg along with the correct
partitions, but it's never listed in /dev. This throws an error when
init tries to fsck my /boot partition and can't find the device node.
Similarly, swapon -a can't find /dev/sda3 and fdisk /dev/sda doesn't see
anything either.

My only thought was that this should be udev/hal related, so I finished
the upgrade for those packages, but to no effect. Is there somewhere
else I should look? Again, it's not a kernel support problem - the
kernel is untouched from before, and sda is detected properly in dmesg.
The disk just isn't showing up in userspace. 

Thanks,
Todd