vSphere 4.1 supports up to 128, and vSphere 4.1 Update 1 supports up to 160.
ESX Host Maximums Virtual machine maximums
Virtual machines per host
320
ESX Host Maximums Virtual machine maximums
Virtual CPUs per host
512
ESX Host Maximums Virtual machine maximums
Virtual CPUs per core
25
The achievable number of vCPUs per core depends on the workload andspecifics of the hardware. For more information see the latest version ofPerformance Best Practices for VMware vSphere