When Google Latitude was first launched, there were wide spread scare stories about how it would breach people’s privacy. Google put in plenty of safeguards to ensure that it didn’t, but perception of these things is important. However, I said at that the time that the significance of Latitude was not that peer to peer location, but the potential offered by an API to integrate it into other apps. Well, Google have now announced an API to do exactly that. Suddently the potential of Latitude has increased by some magnitude. See here for a report.