AT&T just joined Apple in shipping out iPhone 4s.
I'm seeing tipsters' order dates of both June 15 and June 16, but I'm not sure if the June 16 ones were ordered on June 15 or not. But yes, we know now both AT&T and Apple are shipping iPhone 4s. So please, enough with the tips on this particular subject. [Thanks tipsters!]
Update: Reader Chris says that he ordered on June 15, but his says June 16. Probably just a late entry in AT&T's logs.