GenericBum has just showcased his (and others) port of OGRE to the PocketPC platform; since the PocketPC includes no hardware 3D acceleration it runs over a software implementation of OpenGL ES. Looks like an interesting project, you can see screenshots of a couple of the (simpler!) OGRE demos running on a PDA in his forum post.
Whilst we officially support Windows, Linux and OSX, OGRE has been ported by 3rd parties to several other platforms, including FreeBSD and the XBox, although we cannot support or promote the latter due to legal issues. It has also been observed by some that OGRE would be particularly suited to being ported to the next gen consoles, which would be great although I suspect that once again legal issues would be the barrier, rather than technical hurdles. We'll continue making OGRE as portable as we can, and who knows where it'll turn up next.