In February 2008 Microsoft released Windows Server 2008.
At that time Hyper-V was still in beta phase. Despite that, Microsoft decided to take some serious, unprecedented risks and included it in the RTM version of its server operating system.
The actual RTM version of the hypervisor didn’t come out before June 2008.
The customers that wanted to upgrade could download a stand-alone package or just connect to the Windows Updated service.
At today the situation is still the same: who downloads Windows Server 2008 has to install Hyper-V beta and then upgrade it in some way.
Microsoft will fix this with the upcoming Service Pack 2 for Windows Server 2008, which will finally integrates Hyper-V 1.0 RTM as part of the OS.
The RTM-Escrow of this SP2 was released just yesterday and this means that the final release is really near.
It’s ironic that this happens now that Hyper-V is already in 2.0 beta phase.