Oliver blogged about the work he's been doing lately to allow Doom 3 to run over OpenGL ES 2.0 with EGL. This work would allow for Doom 3 to run on mobile devices, well, assuming the hardware is fast enough to keep up with the engine and game content.
Oliver is the same open-source graphics developer that previously brought the Quake 3 engine to the Nokia N900. On the Phoronix IRC channel (#phoronix on freenode.net), McFadden mentioned he's doing this Doom 3 mobile porting just as a hobby. He also mentioned on the Phoronix IRC channel, "I have to think a little about how the game (either single player or multiplayer) could run on embedded hardware, where you do not have the traditional controls...auto-aim sounds like a good and easy idea initially, but you quickly end up running into many corner cases and/or just annoying the player."
Embedded below is a screenshot showing x86_64 Doom 3 on Linux with OpenGL ES 2.0 with GLSL. This work by McFadden is still a work-in-progress, but it's certainly moving along.