During the Q&A session of Carmack's keynote, the Linux support for Rage was brought up. Carmack, sadly, admitted the Linux support isn't a huge priority nor even the Mac support. Right now they're working on getting Rage out the door for the PC and consoles. Carmack concedes that the Linux client is basically at the bottom of the totem pole.id Software has ported their games to Linux in the past, id Software remains an open-source friendly company, and previously Carmack has said id Tech 5 would likely come to Linux, albeit not on the launch day.
There's still hope that id Tech 5 / Rage is coming to Linux, but it sounds like Linux gamers may be waiting a while before seeing this next-generation game appear natively on their favorite Linux distribution.