Grsec in the kernel eta?
(Oddly, grsec itself has expressed opposition to Rust in the kernel, I think on the grounds that their custom GCC plugins can't cross the language boundary. Now that there's work on supporting Rust in GCC itself, I'm not sure if that objection still applies.)
More seriously: many different security improvements are filtering into the kernel idea-by-idea, insofar as folks working on kernel security do the actual work of making them fit in with the kernel, and/or coming up with better alternatives.