So the long wait is over. You can now download vSphere 4 from http://www.vmware.com/download/vsphere/.
I've been patiently waiting for this release as I should now be able to fully and openly discuss the bells and whistles of the product without breaching the private beta confidentiality agreement.
I've used vSphere4 for quite a while now and I can tell you that it's a very good product. Well done VMware. Now that VMware's build work is over (for now), our work starts. Most of us will now be planning the upgrade of our environments to vSphere from VI3. Sounds like fun! Bring it on!