It never occurred to me that after upgrading the Mac from Leopard to Snow Leopard, my printer (HP Laserjet 1020) might no longer work. I had to download a special driver to get it to work with Leopard, and I guess I assumed that driver would still work. Sigh. If I'd actually thought about it, I would have done some research before taking the OS upgrade.
My choices seem to be: (1) revert to Leopard (I don't even know if that's possible without doing damage), (2) wait for a fix (prognosis unclear), or (3) buy a new printer. I wasted a lot of time under Leopard trying (4), network the printer using my PC, so I probably won't try that again. (The Mac still needs a driver, whether the printer is local or remote, so that's not likely to help.) I'll continue with Google research tomorrow; so far the only solution I've found involves downloading a 750MB package, compiling code, and doing lots of fussing.
I realize that this is HP's fault, not Apple's. It's frustrating because I've been using HP printers for more than 15 years without issues and when I bought this one I never thought to check for Mac compatibility. (At the time I wasn't planning to buy a Mac.) It's a peripheral; at some level I expect it to just work.
On the other hand, it's worth noting how easy the OS upgrade was otherwise. Insert disc, confirm intent, leave for an hour, and there it was. I was never willing to attempt an OS change under Windows. This is the only major problem I've seen so far. (There's one minor one that I'll probably just have to get used to; they changed a color that I'd rather they not have, but there doesn't appear to be a user setting for it.)
From a comment:
I wasn't going to buy it yet. Dani wanted it, it sounded benign, and the family pack was cheaper than individual purchases, and I guess I bought into the "things just work on the Mac" mindset (even though my printer hadn't before), so I said sure, get the family pack. What I should have done was say "sure, get the family pack" and then set it aside for six months after he upgraded his machine, but I didn't think it through. I never bought a Windows OS in the year it was issued; why did I upgrade this one right away? Stupid stupid stupid.