OSDev.org

does any one know if there are any mobile phones you can get where you can replace the OS so you could program your own? any one dabbled in such areas?

You would need to do some serious reverse engineering work on the device.. Finding documentation for any chips used in the device, The CPU that is being used.. etc..

It would probably take time, but anything is possible.. It would probably be easier to do on a device that's already using Linux.

http://www.linuxdevices.com/articles/AT9423084269.html

There would probably be a lot of hardware on the device that you won't be able to utilize though..
(Like being able to use it as a phone anymore..)

some of those phones make reference to this:
http://handhelds.org/moin/moin.cgi/HaRET

im not really intrested in reverse engineering, but could be cool to make an mobile OS if i could find a phone with the appropriate documentation

Anyway, JPC is a cool project too, it is meant to be a DOS/other OS? emulator for Java. You know that Java has it's portability - should we see booting MS-DOS 1.0 (or FreeDOS) on your MIDP2 compatible mobile phone? Maybe someday. I can't wait when it will be finished (with src) and even running on my SiemCX65 or k510i !

Home page:
http://www.physics.ox.ac.uk/jpc/

inflater

take a look at ipodlinux they provide source to their iPod OS so you won't have to completely lookup all the docs to the hardware.