What is it?

"The Microsoft Solution Accelerator for Business Desktop Deployment (BDD) delivers end-to-end guidance for efficient planning, building and deploying Microsoft® Windows® Vista and the 2007 Office System."

Al's take:

"All the documentation, tools and templates you need to get up to speed with the new tools and the best practices to roll out Office 2007 (and/or Vista or anything else). It's like the MSDN library for SOE deployment."

This post is cross posted on Alistair's WSS 3.0 powered blog and his MSDN blog.