MPS is very close to version 1.0 and we released MPS 1.0RC today. You can download it here:
http://download.jetbrains.com/mps/MPS-4118-windows.exe
http://download.jetbrains.com/mps/MPS-4118-linux.tar.gz
http://download.jetbrains.com/mps/MPS-4118-macos.zip
http://download.jetbrains.com/mps/MPS-4118-src.zip
http://download.jetbrains.com/mps/MPS-buildTools.zip
Let us know, if you have problems with it.