Foursquare is a way for people to advertise to advertisers, Twitter "friends", and everyone else the fact that you're willing to be advertised to. That is, you spam to be spammed. It's basically awesome for marketers.

Foursquare is the big fish when it comes to location-based services which has already been heavily early-adopted, just not so much in Vietnam. So while LBS has now begun declining in the US (from 5% of Internet users to 4%) , Foursquare will still grow (from basically nothing) in Vietnam until people get the message: the cool kids everywhere else have already gotten bored playing Foursquare.

Location-based service is a trend that I think is here to stay.

Social sites like Facebook and Yelp have added geolocation features to their sites (see Facebook Places), which just makes sense for most people. We don't need yet another place to organize our people when we've already done that with FB or Twitter. And Foursquare will only be a subset, a small subset, of your current social network, and generally speaking, a network is more powerful/useful exponentially based on the number of connections. For most people, nobody wants to use 4sq because nobody else (they know) is using it.

The question: Is Foursquare a useful product by itself, or just a feature that sits atop a real site?

(As the 4sq meme depends on Twitter to propagate, what if Twitter blocked all 4sq as spam and expanded their geolocation tagging features?)

Currently, Foursquare differentiates itself from competitors with "badges" and "mayorships", which may, in the future, lead to rewards for repeat customers. To get those rewards for 4sq users, the company may need to hire sales staff like crazy like Groupon did. The game mechanics of checking in repeatedly in order to gain virtual status is also an invitation for cheating, which is as easy as going to 4sq's website and saying you're somewhere you're not. Game mechanics may work great on other sites but it's not being copied by other LBSs (but see SCVNGR). And as uninteresting as most automatic check-ins are when broadcast over Twitter, automated announcements from badge/mayorship changes on Foursquare are neither useful nor novel anymore.

Foursquare grows because its users are overly open about announcing their locations, and 4sq wants as much free advertising as it can get. But the dark side of this is crazy people stalking you in real life, and burglars knowing when you're not home (http://blog.sheasylvia.com/post/809428679).

So what's the future for Foursquare and location-based services? As I see it:

1. Existing social business directories (like Yelp) just make LBS another feature. They already have the locations and the users and useful user-created content on those locations, and they have the attention of businesses. But every city doesn't already have a dominant social business directory so this may be a play for someone who wants to jump in both spaces at once.

2. Existing social networks integrate the feature well. You probably don't care where anyone outside one of your existing social networks is going. And you probably shouldn't let anyone outside your inner social network know your every move. But does Facebook care enough about this space to pursue it with sufficient resources? Will they wait awhile for the dust to clear and then acquire a 4sq clone?

3. Existing businesses run check-ins by themselves. The status quo, stamped cards for repeat customers: Buy 10 coffees, get 1 free. The idea of "mayorship" is forgotten. Individual websites install a simple widget to check-in, or let customers check-in by tweeting. These businesses never got called by Foursquare salesmen anyways. Aggregators pop up that list all local repeat customer programs. The big promise of a single site for all check-ins fizzles.

4. Nobody wins for now. Nobody is able to get businesses to adopt in sufficient numbers to keep users interested. People get tired of checking in after realizing there really is no benefit. By the time a critical mass of businesses are switched onto the idea, we are at LBS 2.0... and Foursquare has long lost its first-mover advantage as well as the money from the current round of funding. Whether users continue to use it or not, Foursquare needs to either make money soon or convince people to invest more money in them, otherwise they fail. Or Facebook picks them up for cheap.

5. Google Maps. Maps and location naturally complement each other. And Google already is a business directory. Is there a social Google Maps in the future?

6. The real value to users isn't discounts, but rather the chance to meet and talk to people online who are physically near you, not even necessarily tied to a store.

7. Foursquare creates the mainstream LBS market and stays top dog by adding some great new features, dropping focus on gaming, and addressing complaints about accuracy and privacy. It will have to beat all contemporary clones and battle for every city. As for accuracy, infrastructure improvements will come in coming years regardless of whether 4sq exists or not, like upgrades to GPS.

Or maybe none of those things will happen. But I'm not going to bet that #7 is more likely to happen than the first 6 possibilities combined.

P.S. Want to filter canned 4sq messages from your twitter.com feed? Check out h8sq: http://www.saigonist.com/h8sq