Need further proof of the demise of the PDA?

"Palm hasn't released a new PDA in more than a year," noted Todd Kort, a principal analyst for Gartner. Both Kort and Strother said that lower smart phone prices bring about a simple type of mathematics that will further contribute to the decline of the PDA.

"If people need a pocket organizer, and if they buy a new phone every year or two, they'll start thinking whether they want one device for $200 or two devices for $100 a piece," Strother said. "It only makes sense to get a smart phone. So lower smart phone prices will further erode the PDA market."

Of course, while PDAs are headed down, smart phones have no place to go but up. Strother said that, in the most recent quarter, only about 2.5 percent of all phones sold were smart phones. That's an increase over the same quarter a year ago, "but it's still small potatoes," he said.

Gartner's Kort predicts, though, that smart phone sales will start ramping up quickly. He said that, worldwide, 49 million smart phones were sold last year and almost 80 million will be sold this year. Overall, almost a billion mobile phones will be sold worldwide this year, according to Gartner. That firm measures sales and defines smart phones somewhat differently than does NPD, causing a discrepancy in sales statistics.