WiFi has been free at Starbucks in the USA since July 2010. Before that, a registered Starbucks card got you free WiFi.

It's free at all Starbucks now. Makes for a much laggier experience though, since everyone is up on that bandwidth

In the UK it's free if you have a registered Starbucks card (which doesn't cost anything).

It's free at the Starbucks where I live.