Google Latitude is popular among the Google faithful as a way to "check in" at locations on a map. Android phone users especially have ease-of-use for functions like this (see video below). But, now Google has quietly added another wrinkle to the Latitude functionality.
Now, when you check in to a given location, your presence is noted on a leaderboard and you earn "points". You can get "ranked" based on your frequency of visit to that location. This put Google Latitude right in Foursquare's territory. Google is not making a big deal out of this functionality, yet. But, in their quest for world dominance, it may come in handy later.