> And does that mean that you store those pages in your database and use your own ranking algorithm, or are you using their ranked results for a query and then rearranging them on the fly?

I have looked at those search APIs and they don't let you write your own ranking formula. They just give you back 10-20-30 top results. There is no info on term frequency, inverted document frequency, pagerank or any other component of a decent ranking formula. So you can rank yourself the pages from your own crawls, but you can't merge this nicely with the API results.

If I were Garbiel, I would merge them in some crude way basically assuming my results are better, and add those URLs to the list for my crawler. The top URLs for all one and two word queries aren't that many.