I am by no means a versioning expert, but common sense tells me that tracking the revision of something should be done within the versioning software, that is it's purpose after all. However, revision number is almost too precise to use a tracking tool. Keeping a more abstract (Major.Minor) version inside as comments and a more precise Revision number inside svn for specific tracking would be the best. This seems to be the most generally accepted practice, at least in my opinion.
~Sean
