Windows Phone 7 Series getting one chassis spec at launch, two more in the pipe?

If we had it boil it down, the singular image burned in our brains of Windows Phone 7 Series so far is that of a large, nondescript slate -- the so-called "dogfood" device being passed around internally for the platform's development -- and although Microsoft isn't talking specs at this point, it's widely believed that this phone roughly represents the Chassis 1 spec that Redmond is passing around to hardware partners. Is this the only way you'll be able to get your WinPho 7 served to you, though? We might yet be months away from an official answer, but a pair of Microsoft developer evangelists on an Australian podcast are saying that Chassis 1 (full touchscreen, gigahertz processor, and dedicated graphics acceleration) will be the sole option at launch, with Chassis 2 and 3 following on after that. 2 is said to be "more like a Palm Treo" with a dedicated QWERTY keyboard, while 3 remains a mystery, though there's some speculation on the podcast that it could be a candybar -- a form factor that's becoming something of a lost art these days, particularly among smartphones. The speakers note that there's a lot of value in offering some form factor variety -- not everyone wants a keyboardless slate, after all -- so the real question might be how quickly after initial launch we'll see some of these other chassis filter down to retail.