The prospect of the world's largest social network entering a market would be enough to make even the most established company re-evaluate its strategy.

When that sector is still finding its feet however, uttering the word Facebook has the potential make the average start-up CEO break down and weep.

Location-based social apps are hot property at the moment with developments and deals from the major players such as MyTown, Foursquare and Gowalla a regular occurrence.

But rather than taking on each other, the feeling is each has one eye on Facebook's expected entry into the marketplace.

Widening support

As a result, it's no surprise that support from the development community is being courted. The relatively new Gowalla released its API earlier this week, the company using its blog to state its intention to bed the service into a wealth of other apps.

"User-created and curated content is central to Gowalla. Every spot in our database is created by hand, on location, by the community - reflecting the real interests and creativity of the users," it said.

"The Gowalla API takes the creative potential to the next level. We’re eager to see what this community creates next."

Meanwhile, rival Foursquare has been building on the deal it signed with Bravo TV in the US by linking-up with restaurant guide Zagat, premium TV channel HBO and its parent company Warner Bros.

Marching on its stomach

Such deals are designed to encourage users to check in from as many locations as possible. For example, Foursquare hands out 'foodie badges' to those who visit Zagat-rated restaurants in certain cities, and promotions are planned for specific TV shows that tap directly into their respective fanbases.

"We saw thousands of Foursquare users checking in to Zagat-rated restaurants, and saw an opportunity to present content to them as well as engage them in game-play," Zagat senior product manager Ryan Charles told The New York Times.

"There's an added incentive for users to be the mayor of a Zagat-rated restaurant. Also, visitors to our site who may not already know about Foursquare will learn about it. It’s a great cross-promotion."

Shadow of the beast

None of the current line-up is able to compete with Facebook when it comes to linking your check-ins with your online network of friends however.

Indeed, most use it, and similar networks, as the basis for populating users' contact lists.

"Facebook could build its own location-based database overnight," points out Keith Lee, CEO of MyTown developer Booyah. "With 400 million users, it would supersede any other location-based app out there."

And that's one of the reasons, Booyah is looking at the potential of using Facebook as a platform for future apps; using its reach in a co-operative rather than a competitive way.

"We're designing products that work across different platforms whether that's iPhone, mobile or Facebook," Lee says. "You can drive great viral promotion that way."