This new release of ESX/ESXi 3.5 comes with the following enhancements:

  • Increase number of vCPUs per Core Limit (from 8 to 20)
  • New supported servers, NICs and storage IO controllers
  • New supported Guest Operating Systems

… and many more improvements and bug fixes.

ESX Server 3.5 Update 3 Release Notes
ESXi Server 3.5 Update 3 Installable Release Notes