You can now do some slightly fancier things with location queries in Google Base, including the good old bounding box.
I am actually a bit surprised to see this. Base has not had the kind of recognition/adoption that I figured would be required for it to get the development resources it needs (an anonymous Googler once said that the problem with Base was that I was the only one who had heard of it). They still have quite a way to go though… For instance, I need a way of uploading KML representations into a column, and of course Base needs to be swapped in as an open back end to MyMaps. :)