Update on the iBook: seems it dropped so hard that I cracked the screen bezel (the white border around the LCD screen), cracked the hinge, and cracked the internal frame of the notebook - i.e. the bit that everything else is screwed on to. The good news is that these parts are relatively cheap (total bill will be less than $300, which is a relief after hearing 1k yesterday). The bad news is that a drop hard enough to crack the internal chassis ... well, let's hope nothing else is damaged.
As far as I can tell, my data is alright: I make it a habit to back up to an external drive as often as I can, and as luck would have it, I backed it up just a few hours before the accident. The iBook remained functional enough for me to retrieve some more data after. I wouldn't like to have to reinstall all my applications though ...
I mentioned that I had been trying to fix a wireless connection that had gone all wonky on me when this accident happened. Well, fixed it - by going out and getting an Airport Extreme base station to replace the old Airport (non-Extreme, very Sedate) base station.
The one silver lining in all this? The Firefly DVD, which I've been watching every night. So good, I think I'm going to watch the whole series all over again.