I've only found 3 although I've not exhaustively searched all the areas. The on in Rassana is biggest, then Groddle Forrest, then Tamilla. I won't say where though cos its more fun to find them yourself
I found one in Groddle almost instantly -- it was on my home street :) Really gonna miss living "on" a particular street. If there's only three in existence, I'll go search for 'em, but I'd like to know for sure -- any staff around?