Templates from other org's will only show up for Org admins, not normal users. The idea (and one I think needs better rights management around) is that a admin from one org would place an item in a catalog for other admins to see - if other org admins like the content they would make a copy in a catalog they have so their normal users can use it.
(This leads to many copies of the same item in the system, but it does make sure org admins decide what users in there org can see)