Additionally, the Nokia Lumia 800 is excluded from the deal.
How it works (instructions via SD):
1) Get an old smartphone (you may already own one); Android, BlackBerry, iPhone, PalmOS, WebOS, Symbian
2) Get it activated somehow (although not every store checks, some do, so you'll want to make sure it has phone and data on it when you go into the store).
3) Go to your local B&M Microsoft Store and tell them you want to take the "Windows Phone Challenge."
4) Lose the contest.
5) Fill out recycling paperwork.
6) Give them your old smartphone (make sure you format it beforehand as you don't get to keep your old phone).
7) Walk away with a brand new Windows Phone with no contract attached.
The phone you bring in can be from any carrier, including regionals like Virgin.
Phones available to be traded in for are the HTC Titan and Samsung Focus S on AT&T, the HTC Radar and Nokia 710 on T-Mobile and the HTC Trophy on Verizon.
Microsoft has a retail store locator here (mainly on west coast): Microsoft Stores