San Franciso's subway system, the BART, is the latest entity to use augmented reality to grab customers' - or in this case, riders' - attention with a message.

Developed by metaio, the application - called junaio - shows transit data such as station locations and estimated arrival times. Riders point the phone's camera and find directions to the nearest BART station and a list of estimated arrivals for the next several trains via text or graphics that are overlaid on real objects.

Interactive Element

Junaio also has an interactive element to it - it lets users tag photos, audio and text in the real world and leave digital "crumbs" behind at particular locations for others to explore. For instance, someone coming out of the Montgomery BART Station could see recommendations left by friends for nearby restaurants or shops. Junaio is currently available free for iPhone 3GS and through a web interface, with a version for Android in development.

$732 Million

Jupiter Research believes more dynamic augmented reality applications and uses are poised to unfold - the consulting firm recently predicted that mobile AR sales will reach $732 million by 2014, writes MarketingCharts.

These will be focused on location-based search; Games; Lifestyle/Healthcare; Education/Reference; Multimedia/Entertainment; Social Networking; and Enterprise, according to the report "Mobile Augmented Reality: Forecasts, Applications & Opportunity Appraisal 2009-2014."

AR technology has been used by the aircraft industry since the 1990s, but a recognizable consumer market only emerged last year, it said. The report also forecasts a significant increase in the availability of mobile AR-enabled devices starting in mid-2010, aided by increased adoption of Android handsets and iPhones.