Since no one's answered....
This question has been asked occasionally in the past. I've never seen a definitive answer for commercial use of Player, but the general impression I get is that internal use is fine.
http://communities.vmware.com/message/1413785#1413785
I would imagine that VMware would prefer you to purchase a Workstation (or other VMware product,) at least for the people creating & managing the virtual machines. There are tools such as ACE that may be useful for these people. But AFAIK, use of Player internally is fine even without purchasing any other VMware product.
