OK, we're back up.
At about 7:30AM this morning we tried to replace a damaged drive on the database and the system would not detect the new drive. When we went back to the damaged drive, it wouldn't detect that one either.
So we had to replace the whole database server. What was supposed to be a 15 minute exercise turned into an all day affair as we scrambled for and configured new hardware. Data was restored up until about 27 hours from the time the site went down - anything that was posted after around 2AM EST yesterday has been lost.
We will also be running the db on 2GB of memory for the weekend (it was 4GB), but will be ramping up to 8GB on Monday or Tuesday. The site might be a little sluggish until then.
We're taking steps to ensure that this doesn't happen again, including refining our db backup process.