Since the iPhone app store came online, I’ve been playing with a number of mobile social networks. There’s no shortage of them: Limbo, Loopt, Where and Whrrl are all attempting to play in the space.

The central idea of mobile social networks is to connect you with your friends while you’re out and about. Unfortunately, they all require you to rebuild your friend list. Early versions of the Loopt app went so far as to spam people in your iPhone’s address book with text messages.

Local events on Where

Here are some of the keys to success in mobile social networks:

• It’s the network, stupid. Getting people to create Yet Another Network won’t work. I’ve already created my network. Use it. My only friend on the iPhone version of Loopt is 2,500 miles away — hardly someone I can run into when I’m out in San Francisco on the weekend. Loopt and Where have Facebook apps, but their iPhone versions don’t seem to tie into them.
• Let me control when I update my location. Location is very personal. Don’t automatically update my location just because I’ve launched your application. I may just want to check something.
• Let me publish beyond your app. Early adopters who try your app are willing to accept that there is a ramp up period, but they aren’t going to do work for zero return. If I my update my status and no one is there to see it, have I updated my status? Let me automatically publish the information I collect using your app to Facebook, Twitter and my blog. Not only does it give me a reason to use your app, it becomes a distribution vehicle for you, providing exposure to my friends who just might say “How’d he do that?” I taught a lot of my friends about Facebook mobile simply by updating my status from my phone. (Facebook puts a mobile phone icon next to such updates.)
• Seed your app with other content sources. If I don’t have friends, at least give me other content that makes your app worth using. Where does a good job of this, pulling in content from Yelp, eventful and Zipcar. If you can, get ego bloggers like Scoble to use your app.
• 128 King St is not a place. Pete’s Tavern is. Whenever posting information, it should include a human understandable version. You’d never post a location of 37.778911, -122.391223; a street address is marginally more helpful. With the margin of error built into GPS and density of urban areas, place names are critical.
• Let me take pictures. For a long time, mobile developers haven’t had access to cell phone cameras. With the iPhone, they do. The ability to take and send a picture makes it easier to communicate a lot of information quickly. And it adds life to your application. (Bonus points for dropping a copy of the picture in my flickr account.)
• Tie into IM and SMS. Loopt claims that the most commonly asked question via SMS is “Where are you?” That claim is probably made up marketing b.s. without any hard data. Nevertheless, it is a frequent question. Make it easy for me to answer it. Let me send an SMS or IM that includes where I’m at (Pete’s Tavern, 128 King St.). To anyone. Include a URL with a map and optionally a picture.
• Don’t spam my friends. What you do with my friends’ contact information reflects on me. If you spam my friends, I will never use your application again. And I will tell everyone you’re a spammer.

Tying into the various APIs I mentioned may seem like a lot of work — and it is. But the alternative is spending a lot of money on distribution and marketing.

See also:

• Improved iPhone invites (Loopt blog)