QR Code and Data Matrix are clearly the two most popular 2D barcode standards at this moment, but which of the two is more popular? Using "qr code" and "data matrix" as keyword entries on Google Trends reveals that Data Matrix has an advantage over QR in terms of search frequency, but the overall trend shows that QR is quickly gaining momentum.
Google Trends also breaks down the data into regions, and perhaps to a lot of people's surprise, Taiwan ranks way up there in terms of search frequency for the the term "qr code". Looking at Singapore's data (compare its graphical representation when sorted by QR & Data Matrix respectively) also reveals how great the Taiwanese interest is in QR Code. I believe this is the result of a group effort by the members of the Open Mobile Internet Alliance, which includes operators, device manufacturers, software providers, and content providers to promote the awareness of mobile barcodes.
From the end users' perspective, they are starting to see QR Codes pop-up around them, on magazines, newspapers, websites, and even produce. And more new handsets that support mobile barcode readers are also coming into market, for instance the majority of the devices by Asus, Eten, GigaByte, HTC/Dopod, and Nokia come preloaded with or supported by QuickMark's barcode reader. With the contents and tools both coming into place, this trend should continue.