"What I can not understand is why nobody tries to go the mobile computing route. I think in most aspects RISC OS can do a lot more than Windows CE or however it is called now. On this years Wakefield Show Bluetooth, GSM and tough screen usage with RISC OS was demonstrated. So (basic) support of the technologie in PDAs and smartphones is there. Would it be really so hard to get RISC OS running on the let say Palm PDAs and Smartphones? "
For an operating system to succeed in the mobile device market it needs to be able to run on a System on a Chip (SoC) processor. [link]
Right now only Symbian is the only Real Time OS that can do that. Windows Mobile is several months away from being able to do so. [link]
This gives you an idea of the sort of overhaul RISC OS would need in order to have any chance in today's mobile device market.