HTC to “Ship” 1 Million G1s in 2008 — Really?

HTC is projecting to ship 1 million G1 phones during the 2008 calendar year.
This is up 67% from their prior estimate of 600k units.
This announcement is puzzling when contrasted with T-Mobile’s previous October announcement that they had already pre-sold 1.5 milion G1s. And this wasn’t counting retail, which was expected to add another 1-2 million units to the total.
Whatever happened to those numbers?
I’d be very interested to see how “shipped” is being counted here.