In a surprising move, the JetBrains team has decided to open-source the JavaSE portions of IntelliJ IDEA 9.0 and beyond under an Apache 2.0 license. They will begin offering two products, a community edition, and an ultimate edition:

Starting with the upcoming version 9.0, IntelliJ IDEA will be offered in two editions: Community Edition and Ultimate Edition. The Community Edition focuses on Java SE technologies, Groovy and Scala development. It’s free of charge and open-sourced under the Apache 2.0 license. The Ultimate edition with full Java EE technology stack remains our standard commercial offering. See the feature comparison matrix for the differences.

Very cool news! The impact in competition for other IDEs (namely Eclipse and NetBeans) remains to be seen, but this certainly brings another aggressive (and already well-liked competitor) to a broader market.