w00t ! All done. I've upgraded the version of WordPress this site uses, from 1.2 to some nightly build of the current alpha, 1.3-alpha5. Everything was more or less smooth, I'm always a bit stressed when it comes to modifying the whole blog :P
Version 1.3 has really nice improvements here and there in the admin section. I'll go now for some live testing, hope everything will work ok :)