Although Windows Server 2008 is not yet released, Beta 3 is publicly available for early adopters to use. Internet Information Server 7 is already released, but will probably not see widespread use until Windows Server 2008 (formerly "Longhorn") is released, since it only runs on Windows Server 2008 or Windows Vista.
There are already around 2,600 sites running Windows Server 2008 on the Internet. Whilst some of the servers running Windows Server 2008 are at Microsoft itself, the majority are not, with developers and hosting companies taking advantage of Windows Server 2008's availability under a Go Live license which allows the beta to be used for testing or in a live environment without cost.
Once it is released, it could be expected to take a long time for large numbers of sites to move over to the latest version; it took several years for the installed base of Windows Server 2003 to overtake Windows 2000, and there are still some 5 million sites running on Windows 2000 even today.
Source:→ Netcraftmicrosoft, windows server 2008, 2600 sites, internet