Finally. The new eclipse juno milestone 7 got a new launcher to support Java 7 with OpenJDK on OSX. So you dont need to build a custom shell script in your eclipse.app anymore.
Now that Java 7 is officially released, i hope that other projects will pick this up soon.
Download Juno M7: http://www.eclipse.org/downloads/index-developer.php
Eclipse issue tracker: BUG 339788