The Treo was an instant cult classic, embraced by early adopters but by few others. Its premature reliance on the Treo, however, put Handspring into financial peril and Palm bought the company in 2003, not long after the release of the initial version of the smart phone. With the company, Palm also acquired the now-successful Treo.

"I'd hate to think where Palm would be right now if it hadn't been for Handspring," he said. "It gave them a two-year headstart on everybody else."

Remaining barriers

There are still a few barriers to the unbridled growth of smart phones. A big one, according to NPD's Strother, is that the cellular operators are demanding that users buy expensive data services to go with cheap smart phones, something that consumers and enterprises are likely to resist.

"People are smart enough to know that the price of the phone is only the first thing," Strother said. "And some of the data plans are just too expensive."