The letter addresses Jason as one of their "most valuable customers." Jason also notes that his contract is about to expire, and he's got a few iPhones on a family plan. It sounds to us that, much like a lovelorn teen about to lose his girlfriend, AT&T is pulling out all the stops to keep a floundering relationship alive.
Rumors about a Verizon-powered iPhone have buzzed about like annoying mosquitos almost since the iPhone's introduction. The most recent points at January of 2011, though your guess is as good as ours.
If you're among AT&T's "most valuable customers," monitor your mailbox for an orange envelope. And if you score one of these things, let us know.