What’s cooler and a more potential game changer for medicine, design, entertainment, service and more than AR (augmented reality)– blending digital information atop physical reality? Mobile augmented reality!

An emerging array of platforms, tools and apps use GPS, orientation sensors, 3D graphics, live video, Web services, open APIs and engaging user interfaces into a new class of AR systems for mobile devices. Google is gung ho, Apple is lagging (for now).  Here’s who and what to watch. 

1. Mobilizy

This Austrian AR platform company is best known as creator of Wikitude,which it calls the “first practical augmented reality (AR) mobile application.” Download Wikitude through G1, G2 and myTouch phones in the Android Market Place.  An iPhone version is reportedly in the works. A related community, WIKITUDE.me, lets users and others join in development. Mobilizy shipped a developer API and world browser updates on July 15.   

A similar product for Android phones, called Wikitude.me, provides information on 800,000 points of interest around the world, according to Philipp Breuss-Schneeweis, founder of Mobilizy, the Austrian company that developed Wikitude.me. Much of this content comes from Wikipedia, he said.

Worth checking out: A Mobilizy application for T-Mobile G1 developed by IBM that displayed real-time information, transportation and dining options for fans at Wimbledon this year.

2. Layar

Also claiming “the world’s first mobile augmented reality browser” is this Dutch firm offering services in the Netherlands for Android phones. Look for U.S. rollout later this year. Meanwhile, check out this demo video and how it works (below):

3. TwitARound (Application)

Tech gourmands will be downright giddy with this mashup of AR, Twitter and the iPhone 3GS. See live tweets around your location as well as their origin and distance. Why is a another question… Developed in Webkit (UIWebView/Safari Mobile). Supposedely available soon as an iPhone download app. 

4. Enkin for Android

Early stage handheld navigation project worth watching. Check out demo, blog, documentation and more here. Can I see the two ultra-nerd founders in their own Web hit serial? I think I can…

5. Apple

Thought we forgot, didn’t you? The mobile AR world is holding its breath for the iPhone OS 3.1 update, set for September, which will reportedly include APIs for developers to access a video stream directly from the camera. Developers currently cannot publish mobile AR apps to the App Store because the iPhone SDK lacks public APIs for manipulating live video. A petition from developers hopes to nudge Apple. Unfortunately, users of older iPhones lacking the updated camera hardware and onboard compass will be stuck with old-fashioned unaugmented reality. Here’s a taste of the possibilities – a subway locator from developer Acrossair.