Cearny, bless his little productive soul, has been beavering away at a Linux version of the OgrePlatform library, which implements the windowing system, config dialogs etc which Ogre uses on a specific platform. You can read his report at his web site, where he has some tips for compiling Motif under RedHat 7.2.
Since ToMiC has already proved that the non-platform specific parts of Ogre will build under gcc too (with a few ANSI compliance tweaks which Cearny has also been addressing), we’re on our way to a full Linux version. All we’ll need after this is a new plugin implementing the RenderSystem and related classes in OpenGL instead of Direct3D.