Social Line Connect is a simple iPhone game with a cross-platform backbone. The free app, which looks similar to Connect Four, was added to the App Store over the weekend. The real point of the no-frills game is playing it with friends — even if they don’t own an iPhone. To that end, it’s a also proof-of-concept title for SocialDeck, a new middleware startup that’s created a server architecture for people to play games across several platforms.

Based on the premise that “social interaction is much more important than the actual game play,” as co-founder Anish Acharya put it to me during a recent demo at the GigaOM office, SocialDeck’s games can be played between people using an iPhone and on the web via Facebook, with a Blackberry version said to be on the way as well.

If you have an iPhone, it’s worth a try. Once you install the app, you’re given the option to log into Facebook and sync your friends list with your address book and vice-versa. (Social Line Connect is also the name of the company’s Facebook app, so you can challenge friends from there, too.) Voila, instant game network on your web browser and/or your phone, with a leaderboard and chat window for competing with pals.

As a middleware provider, SocialDeck plans to make money by offering targeted demographic data of users for advertisers, advergaming apps, and rev share with game developers. I just hope they come up with cooler titles. How about a SocialDeck version of the strategy classic X-COM, dudes?