Signing up for access to the bits will require a developer ID, the ID of a published app (belonging to you of course), and the name of your local Windows Phone Champ. Applications for the Preview SDK will only be accepted until Monday, September 17th at 5pm PST. Yes that means tha availability will be limited, but Microsoft assures that most registered developers who do apply should be granted access.
Here is how Microsoft describes the decision for a limited release:
I know that many of you want to know why we simply don’t publically release the full SDK now. The reason is that not all Windows Phone 8 features have been announced and our SDK includes comprehensive emulators that allow developers to test apps against a wide range of Windows Phone features. We recognize that this is a different approach to delivering tools than we’ve taken in the past. Our goal is to generate as much Windows Phone 8 excitement as possible to attract new customers when phones go on sale. This is one of many steps we’re taking to help give you what you (and we) want most.Remember, you can sign up at Microsoft Connect at the source link below.
Via: Windows Phone Developer Blog
Source: Microsoft Connect