Wordman: PS actually has a built-in mosaic filter, of course, but much as your map the results are very "canned"--meaning extremely lovely in complexity, but lacking human elements and verisimilitude. (You map, by the way is very, very interesting--I absolutely love the tiling of the oceans and have already made up my mind to steal that from you. Yoink!)

I have Illustrator, but have never even opened it, so I cannot say if this technique would be easier there. I imagine you are right, since up until the final steps it really is a vector map. If anyone else knows the program, I would love to see them create tiles like I would have had before adding the layer styles, etc., so this could be imported into PS for rendering, etc.