The December CTP (Community Technology Preview) build released out through MSDN Subscription downloads yesterday, build number is 5270.  This build will also be going out to TechNet Plus subscribers too.  The December Microsoft® Windows Vista™ Community Technology Preview (CTP) is the third in a series of early Windows Vista builds being released to an extensive technical community. The CTP program is designed to involve customers and partners in the various stages of Windows Vista development by facilitating timely and relevant feedback. Microsoft Corp. is on schedule to have the majority of Windows Vista features code-complete by the end of 2005, and the CTP program will help enable Microsoft to provide testers with a feature-complete version of the product sooner than for any previous Windows® release.

The December CTP will be distributed to testers in the Windows Vista Technical Beta Program, and is available to more than half a million Microsoft Developer Network (MSDN®) and TechNet subscribers. The December CTP offers developers, IT professionals, and Windows enthusiasts an opportunity to review and test some of the operating system’s significant security and performance enhancements and innovations. It also showcases progress on the overall user experience and design elements in Windows Vista.

As with the previous CTPs, the December CTP is intended for use by developers, IT professionals and the technical community. Given the nature of software development and the feedback process, many of the features in this CTP will continue to evolve throughout the development cycle. End users interested in testing pre-release versions of Windows Vista should continue to wait until the beta 2 version becomes available.

So just what is new in this build?  Key differences are as follows:
• "Pearl" start button
• Reliability of user-requested power state transitions / laptop “closed-lid” behavior
• PC Turnoff
• Dynamic scaling for Windows
• Malicious Software Removal Tool
• Consent UI
• Integrated IPSec/ firewall management
• Application deadlock detection
• Instant off
• WUA: Consistent update experience
• WSUS: Detection
• WSUS: AutoUpdate everything

Also first time the Windows Defender has been available outside Microsoft (formerly known as Windows AntiSpyware) and BitLocker Drive Encryption is also included (previously known as full-volume encryption)

Read the PR for more detailed info!  http://www.microsoft.com/presspass/newsroom/winxp/12-19WinVistaDecCTPFS.mspx