Microsoft released the November 2007 Community Technology Preview of Windows Server 2008 on the Connect website, which makes it available to beta testers.

Note:
This build is not Release Candidate 1.

Availability

Microsoft's goal is to supply new test builds of Windows Server 2008 to MSDN and TechNet subscribers within 14 days of release to official beta testers. If you're wondering how to get your hands on this version check here for options.

Build Information

The Build number for this version is 6.0.6001.17042 v.658 and was built on November 7, 2007. As I explained before Microsoft insists on delivering Windows Server 2008 test versions with build numbers 6001. You'd have to look beyond this initial revision number to keep Windows Server 2008 test versions apart.

Product Key Usage

You can use your existing Product Keys with this version. Product Keys for Beta 3 and Release Candidate 0 are perfectly accepted for installing this newest test version. If you're not planning on keeping your installation for more than a month you could also opt not to enter a product key.

Further reading

Microsoft makes November build of Windows Server 2008 available to testers
Windows Server 2008 November CTP is Here! (6001-17042-071107-1618)
Microsoft makes November build of Windows Server 2008 available to testers
Evaluate the Windows Server 2008 Release Candidate today
How to determine your Windows Server 2008 version
Get Windows Server 2008 now
Windows Server Division Weblog