What to Download

1. Download JetBrains MPS EAP (build #150) from:
http://download.jetbrains.com/mps/mps150.exe - windows version
http://download.jetbrains.com/mps/mps150.zip - other version

2. JetBrains MPS contains IntelliJ IDEA plugin and you need IntelliJ IDEA EAP build #3370 to work with JetBrains MPS EAP build 150. Download the required IntelliJ IDEA build from:
IntelliJ IDEA 3370

How to Get Started

1. Install the required IntelliJ IDEA build (note installation intructions on IDEA EAP download page).
2. Install JetBrains MPS.
2a. On windows run installer.
2b. On other system extract mspxxx.zip and set path to JDK in mps.sh located under %MPS_HOME%/bin directory.
3. Start JetBrains MPS. JetBrains MPS will ask you to install JetBrains MPS plugin.
4. Start IntelliJ IDEA.
5. Start JetBrains MPS.

You will probably want to try the MPS Hello World tutorial.

Additional Information