From the Worldcat Local implementation at the University of Washington:
The user can telescope between institution, consortium and Worldcat.
I am not sure that 'telescope' is the right word here ;-)
Aside: As we know we have different access models for stuff in journals and stuff normally found in the catalog. There is one distinction that I would expect to see more made of in the discussions around 'next generation catalogs'. Think of the 'available collection' (what is published) and the local collection (what is held/licensed locally). With A&I databases we offer some subset of the 'available collection' and then offer some fulfillment options including access to a copy in the local collection if available. With the catalog, we typically offer the 'local collection' only, maybe with some links to 'other catalogs'. Except in the very largest libraries, the catalog is not a general discovery tool. So users will naturally do their books/music/dvd/etc discovery activity elsewhere?