You can read here about the delay in the RTM of Windows 2008. It doesn't affect the launch date of Windows 2008.
Based on the amount of changes that went into the codebase between Beta 3 and the July CTP, this doesn't surprise me to a certain extent. It doesn't really change things overall. Since Vista SP1 and Windows 2008, for the most part, share a common codebase, this is a good thing overall. This will give WSv (Windows Virtualization/Hypervisor aka Viridian) some more time to mature.
I know that my Server 2008 VM builds always boot up much faster than any of my Vista RTM systems do, so when the Vista SP1 Beta launches in a few weeks, I expect my Vista systems will receive the same performance boost that my 2008 VMs have shown.
Now they just need one more Vista edition - Windows Vista Core.
I only have one suggestion to Microsoft for future product launches and PR: Underpromise and overdeliver
If WinFS and all the other aspects of Vista that ended up on the cutting room floor had never been talked about or hyped before they were fully mature and ready to demo, you wouldn't have seen so much bad press about what was left out.
Due to software assurance, they can't take an id Software stance of releasing products "when they are done", so that puts them a little bit in between a rock and a hard place.