Hi josh,
there are no plans for multi-platform support for the EyeX Controller and Engine yet, at least nothing that I can share. Multi-platform is great, but it comes at a cost, and right now we’re focusing on making the user experience on Windows the best we possibly can.
The REX eye tracker does work on Linux (with the low-level Gaze SDK), though, and it might be possible to convince us to port the Gaze SDK to OS X as well.