A OQO Talk forum user got Mac OS X running on his OQO Model 02 UMPC:
The Leopard install is legitimate and works quite well. However, I am still working on two final issues which are video resolution, presently limited to 800x480, and wwan which I have not yet attempted. Sound, wifi, power management, and usb are working fine and the system is very responsive. When I have completed these final tasks I will post a review with further details. I would rather finish the project before providing details which may send some in all directions. I will warn you this project is not for the plug and play crowd but definitely do-able. For now there is a link below to a youtube glimpse of the OQO in Leopardland.