Do you know, it was probably to me that John Carmack first revealed he was intending to release the Doom 3 source code. I’m pretty sure. During an interview for PC Gamer in late 2008, I asked him if he’d be continuing his practice of making previous code available once the next big engine was out, and he explained that with Bethesda now owning id he didn’t know if it would be more difficult, but he was “almost certain we will wind up releasing the entire Doom 3 code base once Rage ships.”
So, with Rage safely released, it’s finally happened, and published under the GPL. Not before an emergency recoding of the shadow tech, after BethSoft lawyers got the squits over a possible patent issue.