Via Dave Winer comes a link to an interesting NY Times piece on the intersection of cafe culture and free WiFi - here's an explanation of the problem that one coffee shop offering free WiFi ran into:

Victrola started providing free wireless access two years ago after customers asked for it. As in hundreds of other cafes, the owners hoped it would encourage regulars and infrequent patrons to buy more food and drinks. But there was also a disadvantage, staff members said: the cafe filled with laptop users each weekend, often one to a table meant for four. Some would sit for six to eight hours purchasing a single drink, or nothing at all.

I can see that happening, and I understand why this shop (explained later in the piece) decided to pull WiFi access on weekends. There's an examination of the different types of patronage such shops get, and how it drives the "culture" of the shop. Interesting stuff, and proof that not every business answer lies on the net :)