Yesterday, I wrote an article about how Web-based, location “check in” services, while massively hyped, just aren’t living up to their expectations, generally because Americans don’t really want to be found at all times.

Today, Loopt (News - Alert), a GPS sharing system that allows users to visualize one another using their smart phones and share that information, appears to be willing to take quite a step to attract users. The Mountain View, California-based company has partnered with Virgin Atlantic airlines and is offering buy one, get one free airline tickets to two beach destinations in Mexico to users who “check in” using the service in select locations in San Francisco or Los Angeles. The promo will benefit both companies: Virgin Atlantic has just begun offering flights from the U.S. to Mexican resort destinations (notably Cabo and Cancun).

According to SFGate, the online news vehicle of the San Francisco Chronicle, users can receive the flight vouchers by checking in at SFO or LAX airports or “one of a handful of taco trucks in both cities.” According to the New York Times Bits blog today, visitors to the “Border Grill taco truck on Hollywood Boulevard in Los Angeles or the Los Compadres taco truck on Folsom Street in San Francisco from 11 a.m. to 3 p.m. on Tuesday will get two tacos for $1 and two tickets to Mexico for the price of one, while supplies last.”

This is thought to be Loopt’s attempt to gain some spotlight back from FourSquare, Loopt’s younger yet more successful Web-based check-in service rival. (And presumably Border Grill’s attempt to sell a lot more tacos.)

Yesterday, in a separate news release, Loopt announced that former Yahoo alumni and mobile technology executive Steve Boom will join the company as its first-ever president. It will presumably be Boom’s job to try and take back some market share from newer rivals in the location-based social services, including not only FourSquare but Gowalla and Facebook’s new Places service. Loopt’s co-founder Sam Altman (News - Alert) will continue to serve as CEO.