> Internally, Racket's intermediate compatibility layer over operating-system facilities has been moved into its own library, "rktio", so it can be used in future Racket implementations.

Presumably by "future racket implementations" they mean the Racket 7 move to Chez Scheme: https://news.ycombinator.com/item?id=13656397

Also, this seems like a neat thing for people needing to deploy racket code x-platform:

> Racket supports cross-compilation of executables in more cases, including executables that depend on packages for foreign libraries.