Article in APC Magazine states that Google had released embeddable maps and maplets
“Mapplets can also be combined together. For example, a website that provides vineyard listings has the results plotted onto Google Maps, and this can then be combined with another Mapplet from a website called Panoramio, which shows photos from different places. Result? You can see photos from vineyards in a region to plan a scenic weekend away.”
Video on Google maps here
Third party developers create localised map content/directories/tools such as fuel prices which can be added to your own custom maps.
Some links here:
Article in Business week called: Mix, Match and Mutate : “Mash-ups” — homespun combinations of mainstream services — are altering the Net
http://platial.com/mapmaker embeddable map widgets and map making tool