In December of last year, augmented reality (AR) browser makers Layar chose to pull its iPhone app from the App Store due to frequent crashes reported by users. They thought it was better for their brand to remove the application than to promote a faulty product. As we've mentioned in the past, Layar had hinted that a revamped iPhone app would be out near the end of February, and earlier this week they released just that.

With the relaunch of their iPhone app, Layar rejoins acrossair, Wikitude and others now vying for elbow room in the mobile AR space. Layar boasts one of the largest collections of points-of-interest (POI) data sets and now that library is available again on the iPhone. The usual suspects can be found on Layar, such as Flickr photos, Google search, YouTube videos and Wikipedia articles, but one of the more unique layers on the app is Foursquare integration.

Users can use the Layar AR viewfinder to find nearby Foursquare locations and by linking the app to their account can check in without leaving Layar. There is also a feature in each layer to view entries on a map, or in list view. The map is especially handy for Foursquare integration because Foursquare's own app disappointingly doesn't support a map view. An equally interesting layer to investigate is the Recovery.org layer which shows you which U.S. organizations in your area received funding (and the amount they received) from the Recovery Act.

"The new Layar Reality Browser has a re-engineered engine under the hood. This new engine makes the application light, stable and very quick," the company said on its blog. "It is ready to handle all the current layers and it is a good base to realize all of our exciting future plans."

Layar's return to the iPhone platform comes just in time for the company's new layer marketplace which will allow developers to charge users for their content; in other words, an App Store for mobile AR. If Subway wants to create a layer with all of their locations and charge $.99 for it's use, they or any other company will easily be able to do that. One could assume that Layar will make use of Apple's in-app purchase functionality on the iPhone, but it would be sad to see Layar lose a percentage of their cut on the purchases to Apple. If anything, that could raise prices on the layers themselves, but that's a whole other argument.

This could be a huge step forward for the mobile AR space. As these applications become more useful, more refined and more popular, companies will be excited to participate in providing branded content in an AR experience. Expect an announcement from Layar in the next few weeks about the launch of this exciting new platform, but in the meantime, iPhone users (3GS only) can go snag Layar's free app (iTunes link) in the App Store.