Forget the Palm ( PALM) Pre for a second, and consider the WebOS software platform it runs on. Palm is inviting developers Thursday to start working on applications for its new mobile phone operating system. The move comes a day after the company gave another impressive demonstration of its hotly anticipated Pre touchscreen phone at the CTIA wireless show in Las Vegas. And while gadget fans came away just as impressed as the last time Palm showcased its wonderphone, investors found even more to love in the phone's WebOS operating system. Granted, it was a limited demo, but according to sources on hand, including staff from TheStreet.com, there was one clear takeawy: WebOS looks to be a viable contender in the still unfolding smartphone operating system battle. To be sure, the Pre phone will be an important device if exclusive telco partner Sprint ( S) can deliver it on time and for $200 or less. But ultimately it's Palm's WebOS that will determine the company's fate. The measure of success for mobile computing is roughly the same as how we judge desktop performance. Stability, speed and the ability to multitask or jump instantaneously from one application to another are the paramount goals. WebOS scored big points on that front, according to the demo watchers Wednesday. And if this seamless multitasking capability proves to be true once the Pre is in the hands of consumers, Palm will have entered a select category of companies that have pulled that off.