H Feds -
Tableau Server does indeed have a meta-data repository, and we store report definitions (they're only XML) there, among other things.
The article you found referenced in the other thread is pretty much the documentation we have on the thing since there's nothing you really need to do to feed and care for it -- we handle all that. You'll probably find some other indirect references to it by searching on words like "repository"..
Is there anything specific you want to know about it?