The OGSA Glossary is well written and quite clear.  An excellent piece of work that deserves to be published by OGF.

I have two small, and I emphasize small, areas of comment/concern.

Entity/Identity.  An entity is defined as "Any nameable thing."  This implies that to be an entity in the OGSA 
environment the thing must have a name.  Since the definition of "name" is very general (especially the "address" 
component of it), it is hard to say that this is wrong.  but it certainly is a bit misleading.  When one looks at the 
definition of identity ("An attribute, such as a name, that allows one entity to be distinguished from all others.".  
This seems to reinforce the point by implying that an entity only needs to have an identity and that the identity might 
be something other than a name.

Intermediary.  The definition of intermediary is written in terms of message passing.  Since the definition of message 
is very general, this is okay.  However, the definitions of message broker and message service are written in terms of 
intermediary.  So, this appears to be a bit circular.  In practice, a message broker/service is all about message 
passing in a particular context - passing messages over a communication network.  Perhaps these definitions should be 
tweaked to reflect that.