The new Force.com IDE for Spring ’09 is now available for Eclipse. Eclipse 3.4 is still not supported so be sure you’re using version 3.2.2, 3.3.1.1, or 3.3.2. The biggest enhancement in my mind is Code Assistance which includes code completion, error parsing as you type, and class outlines. The easiest way to upgrade is to use the software updates feature in Eclipse.

You can see the release notes here. Enjoy!