Last week, I wrote how location-based services are making loyalty marketing sexy; today Tasti D-Lite has introduced a great example.

The frozen dessert and drink peddler appears to be the first retailer to tie an offline activity, swiping a loyalty card at check-out, with location service Foursquare.

Here’s the scoop from Mashable:

Customers can use their TreatCards — which also double as gift cards — to earn points for purchases, but those that opt in to the social media bonuses will automatically earn additional points. They’ll also update their Twitter and Foursquare accounts each time the card is swiped and points are earned or redeemed.

With the swipe of that card the consumer gets points toward their next treat and Tasti D-Lite gets mentioned to the customer’s social circle.

How long before someone can attend a Vikings football game and automatically announce to his friends that he’s at the Metrodome (Sköl!) or hop on the train and announce she’s on the the Washington Metro blue line? If others can come up with these win-win relationships (free ice cream is a good incentive), there’s no reason for it to not happen.

As Mashable notes, “Finally, the connection between customers’ social media behavior and their in-store behavior is coming full circle.”