Today VMware released the much anticipated vSphere.  vSphere 4 is the upgrade to VI3.5 and will replace the VI name.  VMware has also restructured their licensing [more]to the following:

Small Business:

  1. Essentials
  2. Essentials Plus

Mid-Size & Enterprise Business:

  1. Standard
  2. Advanced
  3. Enterprise
  4. Enterprise Plus

To learn more about vSphere, or to download a free trial, visit http://www.vmware.com/products/vsphere/