The only way to get a decent, halfway consumer friendly deal on AT&T is to game their system by staying past the expiration of your contract in a "grandfathered" deal, i.e. using data on the older Media Net plan, and using unlocked devices.
BTW, I'm hearing that Sony Ericsson's Xperia X10 will only be sold unlocked in the U.S., though AT&T is rumored to get the Mini versions on contract plans.
This summer it'll likely be that or the Nexus One for me, I think, or maybe even an E72, despite its myriad issues. I can't wait around until September-December until Nokia decides to bring Symbian 3 or Meego over here.