Plugin Development Kit: Since the open-source Community Edition was released, we no longer provide the plugin development kit as a separate download. Please see http://www.jetbrains.org/display/IJOS/Writing+Plug-ins for instructions on setting up a plugin development environment.
JDK 7 support
Java. In place refactorings: introduce parameter
Better quick documentation
New nonmodal replace text control with instant preview of replacements (e.g. easier regexps)
Tons of bug fixing
New refactorings for Groovy (Introduce Field)