A lot of information came out about vSphere (new name for ESX 4) was released at VMworld Europe 2009. Here’s the configuration maximums as presented at VMworld Europe:
Virtual Machine Maximums
Virtual CPUs per Virtual Machine – 8
Size of RAM per Virtual Machine – 256GB
NICs per Virtual Machine – 10
ESX Host Maximums:
Hosts per Cluster – 64
NFS Datastores per Host – 64
Virtual Machines per Host – 256
Physical CPUs per Host – 64
Logical Processors per Host – 64
Total Cores per Cluster – 4096
Virtual CPUs per Core – 20
Size of RAM per Host – 512GB
Total RAM per Cluster – 32TB
Maximum Network Throughput – 40GB/s (Maximum of 4-10GbE Network Cards per ESX Host)
Not including the above we’re also going to get: Fault Tolerance, VM Safe, vNetwork Distributed Switch, vShield Zones, vCenter CapacityIQ, vCenter Data Recovery, vCenter ConfigControl, vCenter Orchestrator, vCenter Chargeback and vCenter AppSpeed
Thanks to VMwareTips.com for their post which helped to verify some of this information!