liveforphysics wrote:devorion wrote:You seem to be forgetting the SymbianOS, which is used by more devices than iPhone/Android put together

Done
(i keep hearing that's the most popular OS, yet I've never knowingly seen a symbianOS device in person)
Symbian is what big manufacturers like Nokia use in a large swath of devices from plain vanilla phones to some pretty advanced ones. However, while it is put on a lot of phones, AFAIK it does not have a community of developers the way PALM managed to create for their PDA's and later phones, and others like Maemo, iPhone and Android (in order of appearance) have followed with.
liveforphysics wrote:(is Maemo Nokia N800-N900 specific? I've not seen one, but it looks like decent specs.)
It's open source so in theory anyone could put it on their device if they bothered, but in practice it started with the N770 three or four years ago, and continued on the N800, N810, N900. Since its been taking third place behind iPhone and Android lately, Intel has been recruited and with Nokia on board they hope to relaunch with more backing. I forgot the name of the soon-to-be relaunched OS.
Maemo is unique in that almost all smartphone/PDA/OS functionality is developed by the user base just like with Linux, but unlike iPhone and Android, where the OS and a base set of functionality was developed comercially, then dev kits were provided to third party. B.t.w. Google tours north america giving intros and help to hot to start develop for Android. Look for a free presentation (and maybe free pizza) at a university near you!