According to the latest blog post from Aspyr, the Mac version is now ready and will be released today. As usual information about the Linux version is scarce, but they do reiterate that it's only lagging 2-3 weeks behind the Mac version. This should mean that it will be ready some time in December:
QuoteWe’ll be back to our regular updates next week with some info on the Linux version, which is still tracking well (about 2-3 weeks behind the Mac). In the mean time, have a great Thanksgiving holiday (for those that celebrate it) and enjoy playing Civilization: Beyond Earth!
Next week's update should be interesting as it's bound to be more Linux specific with the Mac version now out.
You can read the full blog post here.
In other Aspyr related news, Geometry Wars™ 3: Dimensions is now out for Linux and can be picked up from GameAgent or Steam