You can have max of 248 Standard vSwitches per host in vSphere 4.x.
Configuration Maximums vSphere 4.0: http://www.vmware.com/pdf/vsphere4/r40/vsp_40_config_max.pdf
Configuration Maximums vSphere 4.1: http://www.vmware.com/pdf/vsphere4/r41/vsp_41_config_max.pdf
What is the maximum number of VSwitches we can create in VSphere 4.x?
The numbers for all these maximums are now very high, as noted above. Also you get have 512 portgroups for each vSwitch and a total of 1016 active vNIC connections on each host.