Mobile Operating Systems Comparison?

dozerbull asks: "I'm working at a Canadian telecom research lab. They are looking into the creation of tools that would facilitate the development of mobile applications. Symbian OS seems to be the lead target platform candidate. There is however a small crowd that is pushing for Microsoft stuff (Pocket PC and Smartphone). How do other systems (Linux and PalmOS) stack up? What would the Slashdot community advise by way of a choice of an operating system for mobile?"