This is an interesting post from Mike Blumenthal, who discovered some apparently trusted feeds going into Google Maps (My Maps):
Well it appears that Google Maps is allowing a limited number of “trusted” partners to provide exactly such feeds directly into My Maps. Merchant Circle with reviews and coupons and Topix with news are providing RSS feeds of their data to Google Maps via My Maps.
There are some pretty interesting aspects and implications here. More discussion later.
Per Mike’s subsequent investigation this appears to be Google indexing RSS feeds and KML files in selected cases. One of the things Google has to be careful about — and no doubt is — is spam in My Maps. Ultimately the best of this data will be integrated into Maps proper, but figuring out a system that protects against inclusion of spam or trivial/garbage listings is a real issue before doing so.