VMware has better than average documentation available for all their products. 

Good starter point is:
http://www.vmware.com/support/pubs/

Knowledgebase:
http://kb.vmware.com/

Community forums. If you have problem, search the forums too! Good way to search is googling for your error message with +site:communities.vmware.com-parameter in the search string. http://communities.vmware.com/

VI3 documentation:
http://www.vmware.com/support/pubs/vi_pubs.html

VMware Server documentation:
http://www.vmware.com/support/pubs/server_pubs.html

http://www.vmware.com/pdf/server_admin_manual.pdf

Technical Resources:
http://www.vmware.com/resources/techresources/

White papers:
http://www.vmware.com/solutions/whitepapers.html

Compatibility Guides:
http://www.vmware.com/resources/techresources/cat/119

Community-tested hardware configurations and/or OSes (ie. unofficial):
http://www.vmware.com/resources/communitysupport/