It turns out that it's nicely automated. There's a kiosk where you feed it your CD (or CF card or other media) and pick the pictures you want; you submit the order, then you come back nominally an hour later and pick up the pictures. Perfectly decent 4x6 prints, and $.24 apiece is barely more than the paper costs if I wanted to make my own at home, to say nothing of the ink, or the time. I'm sure I'll be using this service again from time to time.
I know a lot of people say Wal-Mart is evil and I shouldn't do business there. If I wanted to avoid them, where else could I go that can do decent 4x6 prints from my digital media? I might be convinced to pay a slightly higher price, if I didn't have to sacrifice quality and convenience.