Guest post by InfoWorld’s Paul Venezia reviews VMware vSphere 4, what the company has billed its ‘virtual data center OS.’ The bottom line: “VMware vSphere 4.0 touches on almost every aspect of managing a virtual infrastructure, from ESX host provisioning to virtual network management to backup and recovery of virtual machines. Time will tell whether these features are as solid as they need to be in this release, but their presence is a substantial step forward for virtual environments.”