Testers had been expecting the new test builds of both Windows products to debut earlier this month.
Microsoft said on Monday that it is releasing the beta of SP1 to approximately 12,000 preselected testers. Testers are under non-disclosure about the beta build and are not supposed to discuss it publicly, according to Microsoft. (I guess 11,999 testers are under NDA. One doesn't seem to be.)
The final version of SP1 is slated to ship in the first quarter of 2008.
Microsoft officials said they will release to testers RC0 "within the next 24 hours." Microsoft also is releasing simultaneously the Internet Information Services 7.0 (IIS7) Media Pack Community Technology Preview. This CTP will feature Windows Media Services 2008, which Microsoft says will provide two times scalabilty over Windows Media Services 9.0. The new media pack also can be installed as part of Windows Server Core.
Windows Server 2008 RC0 also incorporates the first test build of Microsoft's "Viridian" hypervisor in the form of a Community Technology Preview.
Once RC0 is available, it will be able to be downloaded from this Windows Server page. The IIS7 Media Pack CTP will be available for download here.