Free Meta Programming System 1.0 released
JetBrains, the developers behind the IntelliJ IDEA development environment for Java, have released JetBrains Meta Programming System (MPS) mostly under the Apache License 2.0. The goal of MPS is to make creating Domain Specific Languages (DSLs) for developers easier; JetBrains call this approach "Language Oriented Programming" (LOP).
Development of MPS began in 2003 as a research project, with it's underlying ideas explained in a 2004 article. JetBrains has been using MPS since 2006 to develop some of their products and have now made it available to download, complete with documentation. There is also a tutorial which covers how to create a simple DSL for calculators, including the editor level support. MPS is available for Windows, Mac OS X, Linux and as source code.