Yeah, T-Mobile USA... :)

I realize I can't verify that the service works, but will this be
sufficient so that my phone works 10 seconds after I step off the plane
(if all goes well -- If not, I can roam with my existing GSM service,
but at $1/minute, I'd rather not have to roam more then needed)

The reason I ask, when I activated my GSM phone here in Canada, after
the phone was initially activated he kept me on hold for about 2
minutes, then asked me to power the phone off and on again so he could
finish programming it -- I'm not really sure if had anything to do with
programming the phone, or he was just keeping me amused while he
finished updating the billing system or a riveting game of solitaire,
but I'm wondering if there is any reason my phone needs to be on and in
the service area when I activate, or if the phone will pickup everything
it needs from the network when I arrive?

What it really comes down to is this... I'm trying to save a buck or
two.  My first 20 minutes in the airport are always spend on the phone
(to the hotel for a shuttle, to home to let everybody know I arrived
safely, to the office to make lunch plans, let the boss know I'm there,
yadda yadda yadda), so if I need to add "activate GSM phone" to my todo
list, that's not a problem, I'd rather do it from the airport so that I
can spend the 30 minutes from the airport to the hotel on the phone
without it costing me an arm and a leg in roaming airtime.