I like to hangout in coffee shops. In fact being able to work in one is a perk of being a professor. I have found that most independent (or non-Starbucks) coffee shops provide free wireless internet service (if you purchase something). The only exceptions were a small place in Madison, WI that asked .50 and a lot of places in Chicago. But Starbucks has for as long as I can remember charged through T-mobile for their internet. Until now, Starbucks is offering free internet as long as you get a $5 gift card and use it once a month and register your card online.
In theory if offering free wireless is cheap (perhaps $40 a month for the connection, which might be needed anyways) we would expect all coffee shops to compete with each other by offering free wireless. However, by offering wireless I would guess you get customers who stay at tables longer. Perhaps, Starbucks was trying to select customers who would get out sooner, leaving more tables open.
Starbucks looks like they are still trying to do just that with their free wireless. As this article in PC world describes, internet use is limited to two hours a day and you can’t stream videos or call on Skype.
I’m willing to believe that Starbucks is making the choice on restricted free wireless, to maximize their companies profits. This type of limiting shows, that in some cases you might not want certain types of customers (small coffee drinking campers).