Last year some smartphone specs were leaked out of Microsoft that many guessed were Microsoft’s Project Pink Chassis: a.k.a. the magical Zune Phone. Well Mary Jo Foley over at ZDnet seems to think that this Chassis was actually part of an evolving discussion at Microsoft on how to lock down their phone ecosystem so that they had fewer hardware partners that were required to adhere to much stricter specifications.

On a recent “Frankly Speaking” podcast (feb 20) the Microsoft Australia Developer Evangelist hosts Michael Kordahi and Andrew Coates discuss the three different chassis that will be available for Windows Phone 7 Series devices. Chassis 1, which was the one in circulation already, was for big, touchscreen-only devices with 1GHz processors a-la HTC HD2.

Chassis 2 phones will feature hardware keyboads – either Palm Treo-esque or of the sliding QWERTY variety – and touchscreens. Then there was Chassis 3, which they guessed might be candybar form factor.

They suggested that Chassis 1 devices would be the first out of the gates around Christmas, but offered no details on when the Chassis 2 and 3 devices might be available. We’ve already seen a prototype of the LG “Chassis 2” type design, with a sliding QWERY keyboard, so maybe we’ll see more than just Chassis 1 devices at Christmas?

The sheer variety of hardware devices available will certainly be one of the main advantages of Windows Phone 7. By locking in some rigorous hardware requirements for partners and OEM manufacturers Microsoft can ensure a consistent user experience across a broad spectrum of devices.