I checked into my office on Foursquare the other day and I got a message showing there was a special offer. I thought, that’s odd, I didn’t create a special offer.

When I clicked on the offer is was a special from American Express telling me that if I used my American Express card to buy $10 worth of something I would get a matching $10 credit from American Express.

At first I was confused, but then I saw that a number of restaurants listed around my business also had the same offer. Apparently American Express had struck up a deal with Foursquare (and as it turns out any number geo-locations services) to offer specials directly through Foursquare at locations that accepted American Express (data that American Express would obviously have)

This program has been developing since a June roll out, but it appears Amex has really ramped it up to every imaginable category of business.

As I thought about this a number of things came to mind, but the most important one was that a credit card company had essentially taken over a geo-location service.

Now, I’m not suggesting that’s a bad thing. (For the record, American Express is a client and I happen to think very highly of the folks at the OPEN business unit.)

I am suggesting, it’s an interesting turn of events and here’s why:

• Merchants benefit without having to do anything, but of course, accept the Amex card.
• Shoppers benefit without having to do much more than check in and  sync their card
• Foursquare benefits because all of a sudden it’s worth $10 to check in at a lot of places

The full benefit to Amex is evident only to those that know the numbers, but my guess is that this is a cheaper and way more directly targeted way to get to a user than paying for TV. Plus, when someone checks is on Foursquare when out with a bunch of friends and announces they just got $10 off, I’m guessing some non Amex toting friends take note. This play also positions Amex squarely at the front of the hip line and will likely help remove some of the stodginess that they’ve been shedding for a few years now.

This combination of location, mobile, commerce and local business to reach the end user is quite possibly the digital media story of the year.