The popularity of PDAs has increased signifigantly in the first quarter of 2005 due to growing interest in always-on email, according to a Gartner (gartner.com) study released Wednesday.

The rising popularity of always-on email is re-inforced by the success of RIM's Blackberry, which has become the best-selling PDA in the world. Unit sales of the device have increased by 75 percent from the first quarter of 2004, the study finds.

The brand now controls 20.8 percent of the worldwide PDA market, a soli......