For those that may have missed these

Great article on how to configure Visio Services
http://technet.microsoft.com/en-us/library/ee524059.aspx

A critical piece of insight on what to expect by Chris Hopkins in his 
Visilog

http://blogs.msdn.com/chhopkin/archive/2010/05/03/supported-diagrams-and-entities-in-visio-services.aspx

hth,
al