There are other smartphone operating systems. But, Microsoft's Smartphone is off to a disastrous start with only one shipping phone to its credit and former partners like Sendo dropping it in favor of Symbian OS. The reason for this is simple. Developers have found Smartphone to be more of a work in progress than a stable operating system and development platform.

And Palm OS, while holding on in the PDA field, hasn't anything like Symbian OS' smartphone reach with mobile phone OEMs such as Ericsson, Nokia, NTT DoCoMo, Psion, Samsung and Sony already shipping Symbian OS powered devices.

The simple truth is that if youre planning on developing from the operating system on up for smartphones, Symbian OS, descended from Psions EPOC operating system, is the clear leader both in terms of marketability and system maturity.

If you'e a Palm OS developer, making the shift isn't that easy. Despite the operating systems' similar GUI/Menu bar interfaces and their ARM processor based, handheld architecture, there's a big difference between the pair and their development models.

Porting applications from Palm OS to Symbian OS requires more than simply recompiling C++ code. You must understand the differences between such operating system fundamentals such as memory usage and thread handling. Be ready to make a complete shift from Palm OS' single-thread, event-driven software development model to Symbian OS' multi-threaded, object approach. The differences between developing for each platform are profound. Learning Symbian OS may take you a considerable amount of time.