OK... I've figured it out. The command it was running in mcedit.py was wrong, because I didn't put python in the sudoers file, I just put /usr/share/mcedit/mcemv.py in the sudoers file. Darn me having a line that allows me to do anything with sudo... Attached is a deb of 0.0.8-3, which corrects this bug, and should be in extras-devel shortly.

Thanks, everyone, for helping me figure this out... Remember... this is BETA software :P