Google is launching their own version of FourSquare's check-in incentive, and it will be called Leaderboards. Furthermore, it may come to Google+ and eventually be tied to Google Offers. Obviously, Google's Latitude already has the check-in function, but it is rumored that the feature may be coming to Google+. The premise is just like FourSquare... when you check into a location you can increase your ranking in Google's Leaderboards based upon the number of times you have checked in.
The really cool thing about this concept is that it takes things a bit further than FourSquare. Instead of just becoming the Mayor of your local eatery or coffee-shop hangout that only really amounts to bragging rights, the service may end up tied to Google Offers. This means that as you increase your ranking you could earn perks from the local establishment that could give you coupons & discounts on services and products.
Hmmm.... this is such a good idea, it may be worth it to start checking in as much as possible and as soon as possible, just in case they make it work retroactively.
Source: TalkAndroid and Google Support