While I generally don’t like doing a “Me Too” sort of post, I think the U1 release of vSphere is important enough to recap what some of the other blogs are saying on this. Rather than ramble off what has changed, and what is improved, etc. I will instead point you to some blogs who have already covered it quite well:
Techhead (Simon) – General run down of features and improvements.
Yello-Bricks (Duncan) – More detailed dig into HA/DRS and clustering changes. He also points out that VMotion may soon be vMotion.
PowerCLI Blog – PowerCLI 4.0 U1 is also out.
Virtual-Al (Alan) – Better coverage on the new cmdlets in PowerCLI 4.0 U1
The VMGuy (Dave) – VDR 4.1 also out!
I am sure I am missing a few other sites, but then, these are what had hit my RSS reader already. I strongly encourage you to visit a few and become familiar. Afterall, who knows where there will be a quiz. Finally, there are the release notes: