According to the Pew Research Center and American Life Project the number of US adults who own a tablet device rose from 10% on December 21, 2011 to a whopping 19% on January 15, 2012.  25 days!

The study goes on to tell us who the tablet users are, and to a great extent they are the more affluent.  36% of households making $75,000 or more now own a tablet.  31% of college graduates also own a tablet. 
More tablets in the hands of consumers is good news for marketers, according to a new study from Adobe. Tablet users spent 54 percent more per purchase in 2011 than visitors who use smartphones, the study said, with an average order total of $123 per purchase.

Tablet shoppers spend more than their smartphone counterparts for two reasons, according to Adobe: One, they are more affluent than smartphone users, a finding consistent with the Pew study. Adobe also speculated that tablets are simply more conducive to shopping.

Some other interesting takeaways: Pew found that the number of male and female adults in the U.S. who own a tablet computer leapt from 6% (males) and 4% (females) in November 2010 to 19% (for both genders) in mid-January 2012.