Android smartphone users will soon be able to join the Instagram community, a social network for photo-sharing and one that's long been exclusive to iPhone users. Over the weekend, the company launched an early notification sign-up page — so get in line. We can only imagine how long that queue has become, and there's no telling when Instagram for Android will appear in the Android Marketplace. What is Instagram? Instagram is a free photo editing and sharing app that also has a 27-million member strong social network of iPhone users. Instagram photos are "instantly" recognizable by their retro appearance that photographers can apply with a single tap. There are 16 filters in all, including "Nashville," which creates a vintage-looking image with a photo strip border — you can see how your photo will look all 16 ways on a single screen. But cool effects are only a fraction of the Instagram experience — joining the community is where it's at. Like Twitter, Tumblr and Pinterest , Instagram users follow friends and others whose work they like. New photos shared by those you follow appear in your news stream. For more exposure, Instagram is integrated into Facebook, so when you share a photo in Instagram, it automatically posts to your Facebook Timeline. Expansion on both ends Late last week, Instagram opened the door to 4 million Hipstamatic users, another iPhone app that offers retro filters based on old-style cameras and film. It's a good fit. Instagram provides the social network that Hipstamatic lacks. This marks the first time that photographers can bring photos into Instagram from another source — up until now, they could only share them with other platforms such as Facebook and Twitter. When a photo gets pushed into Instagram, it will bring the Hipstamatic trademark tagging information with it —such as the simulated lens, film, and flash used. It's tough to say how big the Instagram community could get, but grow it will. And no worries about letting the riffraff in — most Android smartphone cameras match iPhones pixel for pixel at 8MP and some feature cameras at 12MP or more.