Timothee Besset's Blog has an update from the id Software programmer that offers a little more encouragement on the prospects of Linux versions of id's upcoming Tech5 engine games than recent pessimistic comments on the topic by John Carmack (thanks Jacek Fedoryñski). While Carmack specifically said, "It isn't out of the question, but I don't think we will be able to justify the work," TTimo indicates otherwise:

It is unlikely the new Wolfenstein title is going to get a native Linux release. None of it was done in house, and I had no involvement in the project. QuakeLive offers a lot of challenges and eats away everything else right now.

As far as idTech 5 (the Rage engine), it runs on PS3 and Mac already. Setting up idTech 5 to run on those platforms early on in our development cycle was a direct result of carrying Linux/Mac support in idTech 4 beforehand. It is likely i will be involved with idTech 5 in the near future, I'll be damned if we don't find the time to get Linux builds done.