Did an aptitude full-upgrade today and there was a lot of updated packages available for Debian Sqeeze (I think it was 17 or something similar). Accepted them and did a reboot.
Now I can't access the raspi. It's not responding to ping nor ssh anymore. I'm not the road (or train actually) so I can not turn on the screen to see what the trouble is.
You are hereby warned, don't perform upgrades of OS via ssh when you cannot trouble shoot locally.