I'm wondering what sort of spatial / geo-enabled database and backend he's running with. GeoDjango with PostGIS and some cronned script to do crawl google maps and do the computer vision stuff for a given area would be what I'd use. He could even go the whole hog and EC2 it, spinning up instances as needed and prioritising the crawling of commonly-requested zip codes.
Alas, Google doesn't allow that - their satellite imagery are for displaying purposes only... I guess it can be argued that storing the imagery, processing it, and discarding after processing is not a violation of TOS, but it is likely that retaining the coordinates of the found objects is a "derivative work", which is prohibited, yadayada.
So I just get public domain imagery from USGS. It is slow, but public domain.
