I'm using a Pi as a server for my hacked-together home automation. It seems to run ext4 and hasn't corrupted in the face of frequent power-offs. Out of curiosity, was there anything special about your setup? Did you track the corruption down to anything specific or was it just random?
Mine are also running ext4. I haven't investigated it too much, but it happened 2-3 times during development (quite frustrating when you haven't backed it up for a while).
On another project we're running 30 Pis simultaneously and before we told the operators to shut them down properly each evening we had at least one corruption a week (which wasn't too much of a problem since we always had some provisioned cards on hand).
There seems to be an UPS solution for the Pi already [1].
