I should go to bed, but I'm having so much fun setting up Debian on my XO laptop.
It was super-easy getting it installed (instructions here); you use the same command for updating to a new version of the standard olpc software and for installing Debian. Or Edubuntu, apparently.
For extra disk space, I blew away the default Sugar/Fedora install -- it's pretty easy to get back to a fresh state, just in case I want to set that up again later.
In 472 megs, I have the base Debian, X.org, subversion, vim, fluxbox, mzscheme, and the Glasgow Haskell Compiler, the install for which pulled in gcc, so was big.