Hmm... trip to the datacenter, or figure out how to reduce the size of the big server's root partition without booting to a CD?
Thankfully, someone else solved the problem, as you only get one shot at it. Here's the summary:
Recompile resize2fs statically and to avoid some check
Add e2fsck and resize2fs to your initrd
Add the commands after the mkrootdev line in the init script.
Create a new initrd, reboot with it, and cross your fingers.
Come back after a game of ping pong and see if the machine is reachable.
Reducing the size of your root partition. (tummy.com, ltd. Journal Entry)