Forget the retro renaissance of 3-D, 2-D is the latest buzzword in mobile circles. After becoming popular in Asia and Europe, 2D barcodes - which pack more data than the traditional linear version - are finally catching on here as a way to make offline ads interactive and mobile coupons more convenient.

Resembling tiny crossword puzzles or geometric artworks, 2D codes allow cell phone users to point at outdoor and print ads featuring the distinctive black-and-white squares to get local information, connect to a Web page or to enter a contest.

A leader in the space is New York-based Scanbuy, whose technology includes a mobile application that converts a camera phone into a code reader as well as a Web platform that lets marketers create and track their 2D codes. A somewhat experimental Scanbuy campaign on behalf of Discovery Communications and Citysearch that placed 2D codes in bus shelters, kiosks and other spots around San Francisco to promote local attractions won the "Best Integration with Mobile" category for MediaPost's 2009 Digital Out-of-Home Media Awards last spring.

Now marketers are jumping in in earnest. Sprint is using Scanbuy's EZcodes in direct mail campaigns, including a sweepstakes to win a Kindle 2; Volkswagen has added them to brochures promoting the 2010 GTI; and BMO Capital Markets featured one in a recent ad in The Wall Street Journal.

Separately, national chains such as JCPenney and Starbucks are testing 2D
barcodes to deliver mobile coupons - allowing users to get through checkout faster by reading coupons directly from phones. And without wearing funny glasses.