We previously announced that there would be a release candidate of 6.6 out on 25 August. However, we are experiencing some stability problems with the current 6.6 sources on some platforms, so the 6.6 RC is delayed until we can straighten things out. On x86/Linux and x86_64/Linux things seem relatively stable though, so if you felt brave enough to have a go with the current snapshot on one of those platforms, please go ahead. Snapshots as usual can be grabbed from http://www.haskell.org/ghc/dist/current/dist/ and the release notes (still subject to changes before the release) are here: http://www.haskell.org/ghc/dist/current/docs/users_guide/release-6-6.html Cheers, The GHC Team