Seattle Times article
Aside from the fact that my daughter has been working for them for almost 2 years, is a shift super and soon to be asst. mgr., has been through pretty extensive training and forum sessions with corporate people and has been told that Starbucks does not corporately support controversial social causes, this was all I could find on the subject. None of which says "WE DO NOT SUPPORT THE GAY AGENDA" or "WE DO". There could be some ambiguous enough wording in there to go either way.
Decide for yourself. Personally, I don't go there enough to really worry about it and my daughter brings home a free pound of beans every week, so I'm not really pursuing the issue. But there again, please don't just stop going. If you want to make a difference-tell them you are leaving them and why. Otherwise, your missing $4 won't be so missed or will be attributed to the economy.