well it probably only takes a Motorola dev an afternoon or two to create a usable 2.2 rom for the milestone, so there should be little doubt that such a build is available internally to Motorola.AT&T and T-Mobile both use GSM in the US, but use different frequencies for their 3G. The Telus (Canada) Milestone is frequency compatible with AT&T, so if you get an unlocked Milestone, you have one of the better options for Android on AT&T.
My guess is JS has a development phone, and either knows someone in Motorola, or is someone in Motorola.
My thoughts also. He seems to have a great technical knowledge of networks and how they operate as well as very good engineering knowledge of the phones. My only problem is, how, when ROW have not decided yet whether to have 2.2 on Milestone let alone start porting it, he has a 2.2 build? I was lead to believe the Droid ones would not work on Milestone.
(ROW = Rest Of World)
with regards to js there are two options: he is legit and a troll, or he is not legit and is a troll it doesn't really matter which.