While playing with the 3.0 EAP releases, you may consider checking out the updated MPS generator tutorial. It has undergone a major rewrite to accommodate for all the recent changes to the MPS generator and to better serve the purpose of teaching the various code generation techniques that MPS offers. The bundled generator_demo sample project, which you find in the MPS 3.0 EAP distro, has been updated, too.
Develop with pleasure!
-JetBrains MPS Team