I don't think he has specifically described one, but this about a store in Tokyo:
"You could buy a burrito there, a lottery ticket, batteries, tests for various diseases. You could do voice-mail, e-mail, send faxes. It had occurred to Laney that this was probably the only store for miles that sold anything that anyone ever really needed; the others all sold things that he couldn’t even imagine wanting."
Other musings by the same character that somebody around here may find of interest:
"Laney had recently noticed that the only people who had titles that clearly described their jobs had jobs he wouldn’t have wanted. If people asked him what he did, he said he was a quantitative analyst."
You have a good memory for Gibson. Actually, I didn't mean "wet markets" as literally described in the article, but something more like "wet markets" as some place to buy wetware or some similar cyber-punkish wet-thingy.