With the APIs from Google Maps and Microsoft Virtual Earth, this would actually be pretty easy to implement. The annotations could be added without too much additional trouble; a wiki could also be added to organize notes about the search.

About the only hard part is acquiring the imagery, in terms of tasking the aerial photos. Once they were taken (and assuming they're digital), stitching them together and converting them into tiles suitable for GMaps/VE is pretty straightforward. There are plenty of tools out there to automate this aspect pretty well.

Any ideas on getting this part organized? If someone can figure that bit out, I'd be willing to make the UI.