I ran across this post earlier today http://www.reactos.org/project-news/reactos-044-released (http://www.reactos.org/project-news/reactos-044-released). It appears C::B now works on ReactOS.
I found this pretty interesting:
http://www.onsemi.com/pub_link/Collateral/AND9371-D.PDF
OnSemiconductor uses also codeblocks as environment for one of their µC