This article should have my first working version of the backup script I use at Quantact attached. It’s very rough, it was the first Ruby code I wrote after I got back. I’d like to do a lot of work to it to make it nice, but it’s not a high priority right now. Aniero asked to see it on irc, so here it is. Read the comments and look for <<...>> for places you need to put in your own info. The Subversion part assumes you have all your Subversion repositories running under one user.
I run this in a root cron job. Feel free to improve and send back to me :)