Hmmm... well, based on various pieces of advice, I've:
1. Repaired permissions
2. Repaired the disk (there were no problems)
3. Cleared the Caches directory
4. Reset the SMC
Unfortunately, this morning, is was suffering from the black death again. This time it was already powered up when I got to it, but everything else was the same - black screen, not responsive to any inputs, etc.
The only thing I haven't done from what was on the above list was clear the Cookies.. I'll guess I'll do that as well, but I'm skeptical.
Has anyone else been on the phone with Apple? Are they aware that many people are having this problem, not just one or two? I'd do it, but my machine is not under warranty (it's a 2008 MBP), and they'll charge me for the priviledge. Does anyone know if they actually monitor these discussion lists?