To some analysts, if you can make cellular calls and access data services through a handheld that has a rich operating system, it's a smartphone; no matter its size and configuration. To others, like Gartner, form and function are equally important.

So while there are those who consistently shout from the rooftops about how the PDA market is dying, Gartner has reliably highlighted how the category—it defines as a data-centric handheld computer weighing less than one pound with two-handed use in mind—is surviving, if not thriving, because of the addition of cellular-wireless capabilities.

By Gartner's count - and definition - 2005 was a banner year for PDAs. Worldwide shipments increased by 19 percent from the year before, to a record 14.9 million units; the best tally since 13.2 million in 2001.

Research In Motion (RIM) lead the market with a 21.4 percent share—up 44 percent from 2004—counting only its traditional square-like BlackBerry models and not the newer 858,000-strong 7100 series, which are more handset-like with a voice-centric design that didn't meet Gartner's PDA criteria.

Gartner principal analyst Todd Kort says, "RIM does not appear to be losing much momentum despite its legal problems and the threat of an injunction. Generally, BlackBerry users are staying put because of the high cost of switching, lack of suitable alternative devices, and the low probability of BlackBerry service being shut down."

Palm held onto 18.6 percent of the market, although it lowered shipments by 25 percent from the previous year. While 2.77 million fewer PDAs left Palm warehouses, 1.95 million Treo smartphone helped make up the difference in the handheld pioneer's bottom-line, but not in this tally.

The top-selling PDA operating system last year, Windows Mobile, which accounted for about half of all shipments, is represented by top-seller Hewlett-Packard and its very popular line of iPAQ Pocket PCs and Phones. The computer and printer giant took 15.2 percent of the market and almost a third of all Microsoft-based PDAs sales.

And while Nokia is primarily known as the number one handset seller in the world, with its S60 interface for the Symbian smartphone platform, enough of its phones were able to meet Gartner's PDA defination—most likely its Series 80 Communicators, including the 9300 and 9500—to enable it to place in the analyst’s PDA hierarchy with 6.8 percent.

T-Mobile, which offers a number of Pocket PC Phones—most of which Gartner would classify as a PDA—rounds out the top five with 5.5 percent of the market.