I already had an awesome talking makefile which commanded me to go and fix my program when it broke by using festival, a voice synthesizer for Linux. I didn't know there was also a plugin for gaim, "festival-gaim".
It's quite funny but I don't think it's a good idea to have your computer reading out loud your messages. And you should remember to log off when going to sleep.
Perhaps I'll try festival as (yet another) wake up method: with a cron I can probably get it to read the news out loud in the morning. I'm not sure yet if that'll wake me up or make me even sleepier, though.