The promotion is on the Starwood web-site, you have to log in as a member and then click on 'partners', then click on 'telecommunications' from the pull down menu to see the promotion. The offer as stated has expired, but I called the phone number listed for AT&T and they said it was still good ... 5000 miles, 30-day commitment (takes about 8 weeks to fully process though).
I read alot of stories about people not getting their miles posted from AT&T, but I'll take my chances and keep my fingers crossed.