Palm plans to announce a new type of mobile device on Wednesday, as it continues its product-line transition from simple personal digital assistants (PDAs) to more advanced smartphones.

Consumer electronics vendors are rushing to develop handsets that offer mobile email and internet browsing instead of merely calendars and contact lists. Apple added fuel to this fire in January when CEO Steve Jobs announced he would launch the iPhone in June, combining the iPod music player with a digital camera, smartphone and touchscreen display.

Now Palm is telling industry watchers that founder Jeff Hawkins will unveil the new device during his talk at this week's D: All Things Digital.

Palm is keeping quiet about the details, even declining to brief industry analysts ahead of the announcement. But one possibility is the Linux-based smartphone that Palm CEO Ed Colligan has promised to release before the end of 2007. Such a device would improve performance compared to Palm's current Treo by running the Palm OS on top of a Linux kernel, Colligan told analysts at the company's annual investor day in April.

Palm will also continue to use Microsoft's Windows Mobile OS. In the PDA segment, vendors used Windows on 62.1 per cent of handsets in the first quarter of 2007, compared to just 0.7 per cent for Linux, according to Gartner.

By continuing to develop applications on both tracks, Palm hopes to win customers by offering them more options with its Treo smartphone than competitors like Research in Motion (RIM)'s BlackBerry, Motorola's Q and Samsung's BlackJack.

Another possibility for Palm is to re-architect its Treo into a more stylish, consumer-friendly device, said analyst Jack Gold, founder of the research firm J. Gold Associates.

"They are being left behind by the likes of BlackBerry and Nokia and Moto as far as device design goes," Gold said. "I wouldn't be surprised to see a new navigation paradigm, but not too far away from a standard phone. They don't want to lose their bread and butter clients, who are mostly business users who want an email device."