This report by Todd Bishop in the Seattle P-I appeared a few weeks ago, but I just noticed it. I had heard the news from other sources, and I’m glad to see it officially confirmed here:
Microsoft … is aiming to integrate all of Windows Vista’s planned features into the preliminary version of the program by early next year, said Amitabh Srivastava, corporate vice president in the Windows Core Operating System division.
Such a step is significant because it lets software development teams focus on fixing bugs in established features, rather than making new features.
Users of the preliminary version “will have a feature-complete Windows Vista sooner in their hands than any previous Windows release,” Srivastava said in a conference call Tuesday.
It’s one in a series of engineering changes that the company has instituted in an attempt to create a greater level of stability and security in Windows Vista. Previous versions of the operating system have routinely been criticized on both fronts.
When we were working on the original edition of Windows XP Inside Out back in early 2001, the constant flurry of changes to core features drove us crazy. As I recall, there were significant changes even between so-called release candidates, one of which was significant enough that we had to rewrite a chapter at the last minute to get the details right.
Everything I’ve seen so far suggests that Microsoft really has changed its engineering processes. That bodes extremely well for the initial release of Windows Vista. It also means that we might have an easier time writing Windows Vista Inside Out.
Ed Bott 
Microsoft’s Windows beta programs have always been a mystery to me. I’ve worked with Windows as a Sysadmin for 9 years, and I still don’t know how to get into the Windows Beta program. I’m aware that the Vista beta is available to Technet Plus and MSDN customers, but I don’t need MSDN and don’t see the value of Technet Plus at the price Microsoft charges. I’d really like to test Vista, but don’t know how to do so legally. Any insight?