According to research firm Gartner Inc., BlackBerry is now the most popular PDA by worldwide shipment count.

Gartner measures these shipments quarter-to-quarter. For the first three months of this year, BlackBerry maker RIM overtook palmOne (mostly for the Treo).

Gartner analyst Todd Kort said the market-leader shift was largely because of an increased preference for wireless e-mail that can be written and managed over the type of Qwerty keyboards that are featured in BlackBerry and other models.

The displacement was quite dramatic. In the first quarter of 2004, palmOne shipped 834,591 units, or 30.5 percent of the estimated 2,736,072 PDAs shipped worldwide in that quarter. BlackBerry moved 405,000, or around 14.8. HP was second with 575,853 (21.0 percent).

How much things have changed. Here are the unit-ship numbers from January through March of 2005, reflected against the total of an estimated 3,419,112 shipped units:

BlackBerry/RIM: 711,000, or 20.8 percent;
palmOne:           : 614,750, or 18.0 percent;
HP                    : 601,352, or  17.6 percent.

For the record, Nokia was fourth with 340,000 PDAs shipped (9.9 percent), and Dell was fifth wih 217,000 PDAs shipped. That was 6.3 percent of the total. Other PDAs accounted for a combined 935,010 1Q shipments.