I saw an link to an interesting site in Robert Scoble's post Paul remixes Google Maps and Craig's List in interesting new way  where he writes

What happens when you mix Google Maps with Craig's List? Paul Rademacher shows us.

This is a cautionary tale for Microsoft: them who has the best API's will get used in the most interesting new ways.

Like Ballmer says: developers, developers, developers, developers, developers...

Actually this has little to do with APIs given that there is neither an official Craig's List API nor is there a Google Maps API. This looks more like a combination of HTML screen scraping for getting the Craig's List data and good old fashioned reverse engineering. I suspect Paul didn't have to do much reverse engineering in the Google Maps case because Engadget already published an article called HOW-TO: Make your own annotated multimedia Google map which shows exactly how to build your own applications on top of Google Maps.

Despite that this is definitely a cool hack.

This shows one of the interesting side effects of building an AJAX site. You basically have to create an API for all the Javascript callbacks from the web browser back to the server. Once you do that, anyone else can call this API as well. I doubt that the Google folks anticipated that there would be this much interest in the API the browser uses the talk to the Google Maps server.

PS: Is anyone other reader of Scoble's blog irritated by the fact that he can't point to anything on the Web without throwing some Microsoft spin on it?