Microsoft promised that sign-ups for a Windows Phone 8 SDK Preview Program would open today, and the company has followed through. Although the near-final kit will be available to current Windows Phone developers, Microsoft says access to the program is limited. A full Windows Phone 8 SDK will be made available publicly later this year once the company unveils Windows Phone 8, but the Preview Program will provide early access to developers.

Windows Phone developers can head over to Microsoft's connect site until Monday, September 17 at 5pm PDT to register. Developers accepted into the program will hear from Microsoft in the "following week with instructions on how to download the SDK." Microsoft says the limited Preview Program, instead of a public one, is due to the fact that not all Windows Phone 8 features have been announced. "We recognize that this is a different approach to delivering tools than we’ve taken in the past," says Microsoft's Todd Brix. Our goal is to generate as much Windows Phone 8 excitement as possible to attract new customers when phones go on sale.

It's still not clear exactly when Windows Phone 8 devices will be made available, but we're hearing that AT&T is aiming to stock the Nokia Lumia 920 on November 2nd.