I guess can why there was such a big jump in Linux's market share - Japan.
I believe that NTT DoCoMo has just released it's first Linux-based handsets and they've obviously been selling very well.
I have to agree with MS Mobiles though, that it's questionable whether these are actually smartphones. They've certainly got a non-propreitary operating system, but NTT DoCoMo's phones (both Linux and Symbian) are locked down so that they will only run Java 3rd party apps.
Still, it shows that Microsoft has got a fight on it's hands from three main competitors now - Symbian, Palm and Linux. Hopefully this will keep Microsoft on their toes and stop them from forming a monopoly. Competition is always a good thing and it'll only lead to better Microsoft products.