Let me start off, by just saying that this site is great, its always entertaining and filled with great data : http://get-admin.com/blog/
I'm very happy that Vmware released 4.1 recently. After the horror stories I read about 4.0U1 we decided to skip them and wait for 4.1. There wasn't a lot in the updates we cared for anyways. There are quite a few interesting features in 4.1, and one of the good things that Vmware has done is finally killed off ESX (after this release). ESXi has been great for us over the last couple years, and I haven't had any complaints with switching over to it from ESX in previous years. I found using update manager was not the most reliable when moving from 3.x to 4.x on the physical systems themselves, so we opted to use the host upgrade tool. This is not a supported method to move from 4.x to 4.1. We will probably have to give the update manager another run, which concerns me. At least its not as complex as upgrading Hyper-v J
I will probably start upgrading our enterprise (not production) systems to 4.1 in the next couple weeks, and I will post my findings on the blog as I go.