This is important, as the newer FNA build should allow the game to work for a long time as well as hopefully fix any lingering issues anyone had with it on Linux.
It was announced by Ethan Lee (the author of FNA, who also ports a lot of Linux games) yesterday on Twitter to let everyone know what the update was for.
Strange it took a while though, since the GOG release in October was the FNA build.
About the game:
Bastion is an action role-playing experience that redefines storytelling in games, with a reactive narrator who marks your every move. Explore more than 40 lush hand-painted environments as you discover the secrets of the Calamity, a surreal catastrophe that shattered the world to pieces. Wield a huge arsenal of upgradeable weapons and battle savage beasts adapted to their new habitat. Finish the main story to unlock the New Game Plus mode and continue your journey!
If you've still not played it, the game is actually on sale on Steam right now for another ~45 hours. 75% off is a steal — grab while you can!