During the Windows Phone 7 Series unveiling on Feb. 15--and afterward, in discussions with Microsoft executives--it became very clear that Microsoft intended to work with its hardware partners to streamline the number of devices running the new smartphone operating system.

This seems the logical move, given that an operating system centered on touch screens will work on a more limited number of form factors. Also, as demonstrated by Microsoft's booth at January's Consumer Electronics Show, Windows Mobile runs on enough (wildly) different models of phone to make it a hair-tearing nightmare for any marketing guru attempting to establish a consistent brand "look" in the manner of BlackBerry or Apple. (Google Android is on the verge of experiencing the same sort of problem, I believe, as its number of supporting devices and accompanying OS variants multiplies over the near term.)

In a Feb. 20 podcast on Frankly Speaking (subsequently seized upon by other news sources), a pair of developer evangelists for Microsoft Australia suggested that Microsoft will limit the number of form factors available for Windows Phone 7 Series devices to three. "Chassis 1" will be a model with a full touch screen and no physical keyboard, reminiscent of the HTC Droid Eris or Nexus One. "Chassis 2" will feature a sliding physical keyboard. "Chassis 3" could apparently be a candy-bar form factor, which is way retro.

The first two form factors are easily pictured, but I'm having a little trouble visualizing Chassis 3. A traditional candy-bar configuration would have too little screen to effectively leverage a touch-screen interface; if it looked something like the Palm Pixi, though, I have an easier time seeing it as something workable.

In any case, Microsoft seems to be making the right move in limiting its hardware ecosystem. The bigger question remains whether developers will jump on a Windows Phone 7 Series bandwagon, something that will start to become clear after next month's MIX 10 conference.