@tgsuperspec: Thanks for your reaction! Maybe you've install the Java SE-6 runtime when your Mac asked you?
When I unzip the .zip file and start it I get the attached message on all of my Mac 
That's not good, since I have a higher version of Java installed on the system.
The message is in Dutch it's saying that you need to install Java SE 6-runtime to open the Arduino-app.
Hope someone knows the solution for this since installing a older Java version isn't a solution.
