This event records if the inventory of hosts has reached capacity of the current version of vCenter.
The maximum number of hosts that are allowed for this edition of vCenter Server has been reached.
Make sure you do not exceed the number of hosts allowed for your edition of vCenter Server.
You may need to update vCenter 4 to Update 1. For more information, see this VMware KB article.
Refer to the VMware Online Documentation for more information.