An independent Linux developer, Robert Beckebans, has ported Doom 3 BFG to Linux. id Software said they would not officially bring Doom 3 BFG to Linux. Late last month though id Software released the Doom 3 BFG source-code. The new source-code combined with the original Doom 3 (id Tech 4) engine source code that had native Linux support made a new port fairly easy.
Beckebans wrote to me on Twitter about his BFG Linux port. Incomplete though with this port is bringing the new sound engine to Linux.
The source code to his Doom 3 BFG Linux port can be found on GitHub under the RBDOOM-3-BFG project. Too bad though there isn't much else to report on with open-source Doom 3.