You might associate the image of a busy, BlackBerry-toting exec with the Fortune 500, but New York-based market watchers AMI-Partners say that smartphone e-mail, calendar, and contact access have trickled down from the enterprise to 31 percent of U.S. small businesses, with another 11 percent of such firms planning to purchase one. And one in five small-office smartphone users plan to buy a newer one in the next 12 months.

Defining small businesses as companies with up to 99 employees, AMI-Partners foresees a compounded annual growth of 6 percent leading to sales of $375 million in devices alone (not counting services) in five years. That's six times the rate of estimated smartphone spending of medium businesses (100 to 999 staff).

The firm adds that RIM and Palm are small companies' first and second favorite suppliers, and that 84 percent of BlackBerry and 68 percent of Palm owners use their smartphones to access e-mail. Three-quarters of Palm and 65 percent of BlackBerry owners access their calendar and contact information while on the go, with more sophisticated applications such as field service/delivery and CRM coming up fast.