The key mark of this release is the improved evaluation model. You no longer have to apply for the free 30-day evaluation key.
Just download the installation package, setup and get started. Your free evaluation period starts when you first run IntelliJ IDEA.
Other remarkable features include:
Tomcat 6 support
JUnit 4.2 support
Bundled Ant 1.7
Keymap for Eclipse users
Miscellaneous fixes and improvements
For complete list of what's been fixed, added and improved, see
Release Notes.