Update on this offer: according to the AT&T rep I spoke to today, the offer is for 2500 Starpoints after each of your first, third, and sixth invoices.
Also, apparently they open a new Starwood Preferred Guest account for you to deposit the points into.
I'm assuming I can get Starwood to combine the points into my existing account. Has anyone ever run into this type of promotion before, and if so were you able to combine accounts?