There's lots of of information on the Technet Desktop deployment page.
To quote from the mail I had telling me that BDD 2007 was release:
BDD is the best practice set of comprehensive guidance and tools to optimally deploy Windows Vista and the 2007 Microsoft Office system. Many changes have been made to BDD to significantly ease the deployment of Windows Vista, including new out-of-the-box imaging technologies, XML-based migration scripts, new tools for image engineering (ImageX and System Image Manager), application compatibility (Application Compatibility Toolkit 5.0) and the new unattend XML format. Another huge breakthrough with Windows Vista is Hardware Abstraction Layer (HAL) independence and language neutrality; this means that our customers can get to a minimal number of standard images across multiple hardware types and languages.
As with any advancement in technologies, getting the maximum benefit requires understanding the tools and technologies. BDD 2007 provides the depth of guidance and tooling to make the Windows Vista and 2007 Office system deployment process predictable and scalable.
To learn more about this solution accelerator, visit the Overview page of the Business Desktop Deployment 2007 or download BDD 2007 now