Do you receive this message?
A Java Runtime Environment (JRE) or Java Development Kit (JDK) must be available in order to run Eclipse
No Java virtual machine was found after searching the following location
Java in your current PATH
In the Eclipse.app/Contents/MacOS/eclipse.ini file put
Pay attention, the carriage return is important after “-vm”
On my computer, after installing aptana studio 3 (http://www.aptana.com), the Eclipse.app/Contents/MacOS/eclipse.ini was overwritten and I had to update the file again