Too much latitude in Google’s location-finder?

Geo-location data is a pretty mouth-watering prospect for mobile marketers, and I imagine Google’s new opt-in application called Latitude — you install, invite your friends, and you can keep track of where  you all are if they say ok — prompts wishful thoughts of Latitude customers opting in to be contacted by Coca-Cola if they pass a grocery store. But not just privacy advocates are already having a bit of a cow — most people I’ve mentioned it to seem to think the prospect of Google knowing where they are is downright creepy (other than my husband, who is already planning on downloading it).  Any thoughts?