Well, the waking Michal up when MySQL goes down idea works. :)
I got paged when MySQL started giving a "too many connections" error around 2:00AM EST. I logged in and got MySQL back up within 5 minutes.
Whatever the cause, it seems to have hit rather suddenly. I have a tool logging the mysql status every minute. There were only a handful of connections until 1:55, and then suddenly no word for nine minutes. So either there's a bug in my logging system or MySQL suddenly started taking forever to connect.
2007-08-11 01:53:02,112:INFO:root:found 4 threads. doing nothing. 2007-08-11 01:54:01,890:INFO:root:found 4 threads. doing nothing. 2007-08-11 01:55:01,580:INFO:root:found 3 threads. doing nothing. 2007-08-11 02:04:02,209:WARN:root:got 'too many connections' error; restarting
It's interesting that the automated attempt to restart failed. I'll have to look into that.
In any case, everything's working fine now. Total downtime seems to have been about 10 minutes.