The payment system for the Palm app store  important if the company wants to charge for certain programs  is still under construction. And most crucially, Palm has yet to open its software development kit, the main set of tools needed to write apps, to most of the thousands of developers who have expressed an interest in creating programs for the Pre.

As a result, some developers are wary of the new platform, said Ben Gottlieb, the president of Stand Alone, which has been creating fitness, game and calendar applications for Palm devices since 1995 but is focusing its new development efforts on the iPhone.

“The WebOS looks like a great comeback, but there’s a little bit of trepidation there,” Mr. Gottlieb said. “Most Palm OS developers I know have moved over to the iPhone. A lot of us feel abandoned, as the platform was neglected for so many years.”

The competition is not standing still. Last week, Apple upgraded the iPhone’s software and began selling a new, faster model. Research in Motion is supposed to unveil several new BlackBerrys this year, including an update to Storm, its touch-screen device. And HTC and Motorola are expected to introduce phones that use Google’s Android operating system.

The stakes are high for Palm, which once dominated the smartphone market with its now-aging Treo handsets and even had a vast constellation of developers who wrote apps for the Treo’s Palm OS operating system. Since 2007, the company has been steadily losing market share in the United States to Apple, R.I.M. and HTC, according to data from Nielsen Mobile, a research firm that tracks the wireless industry.