Epic's Unreal Tournament 3 Linux client has been held up in legal problems, which we initially believed were related to the physics engine, but AGEIA said it wasn't PhysX. Ryan Gordon, the one responsible for the Unreal Tournament Linux ports, has yet to provide the Linux gaming community with any status update or respond to our inquiries. Last week though a v1.2 Linux server build was released.
If/when the UT3 Linux client ever becomes available or we have new information on the matter, we'll be sure to notify you. There is also an active discussion going on in the forums on UT3 for Linux.