As of Q42011, 46 percent of US mobile consumers had Smartphones (reported by Nielsen; according to ComScore that’s up from 27% in December 2010)
In December 2011, 1 in every 5 smartphone owners in the U.S. scanned a QR code with their phone (reported by ComScore)
On Christmas Day 2011, 6.8M Android and iOS activation’s occurred (reported by Flurry Analytics via Mashable)
For comparison, if we use the June Wireless Subscriber info and the Q4/December Smartphone info we can estimate that ~29.7M people scanned a QR code with their phone in the month of December 2011 (up 15.7M from June).
For some interesting perspective, in July 2011 the population of the US was 311.5919M people (yes, that means there are more wireless subscriber connections in the US than there are people!). That would mean 9.5% of the entire US population scanned in December.
ScanLife (code reader and provider) reported seeing a 263% YOY increase in QR scans during Cyberweek 2011.
In April 2011, 70% of Smartphone owners use their Smartphone while in stores (reported by Google via independent research from Ipsos OTX)