woodie: Trams and trolleys are the same thing--a trolley in Europe or Australia is a tram, a tram in North America is a trolley. The Western Railway Museum has an old Melbourne car, I believe, in addition to a hatful of other trolleys and trams.
And then of course there are "light rail vehicles", which they have here in Sacramento, but they're still trolleys even though they use pantographs for power collection...
back to the original question, I have never seen a layout focused entirely on cable cars, and I have certainly never seen one based on aerial cable cars. While a cable-car layout might be kind of neat (it would be a lot like a trolley layout, but even smaller, and without a need for overhead) I can't see a layout of two counterbalanced aerial cars going back and forth being much fun to operate.
I think Roundhouse produced a series of cable car powerhouse kits, and I know Bachmann makes a cable car model (they keep advertising the damn things as "trolleys" on eBay) so it'd be pretty cheap to do a basic trolley layout--just get a bunch of DPM kits for building flats and make a simple "dog-bone" with 6" radius loops at each end.