Do you have a "console" program in /Applications/Utilities? Maybe it will have the full java error in the logs?
Here is what I have in my console log, from the start of the app, to the quit:
20/1/13 12:36:57.629 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: [JavaAppLauncher] Requested [1.5*], launching in [1.6] instead.
20/1/13 12:36:59.065 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: Stable Library
20/1/13 12:36:59.065 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: =========================================
20/1/13 12:36:59.065 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: Native lib Version = RXTX-2.1-7
20/1/13 12:36:59.065 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: Java lib Version = RXTX-2.1-7
20/1/13 12:36:59.459 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: [LaunchRunner Error] processing.app.Base.main(String[]) threw an exception:
20/1/13 12:36:59.459 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: java.lang.ArithmeticException: / by zero.main(String[]) threw an exception:
20/1/13 12:36:59.459 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at processing.app.syntax.TextAreaPainter.nextTabStop(TextAreaPainter.java:497)
20/1/13 12:36:59.459 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at processing.app.syntax.TextAreaPainter.nextTabStop(TextAreaPainter.java:497)
20/1/13 12:36:59.459 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at javax.swing.text.Utilities.getTabbedTextWidth(Utilities.java:242).java:497)
20/1/13 12:36:59.459 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at javax.swing.text.Utilities.getTabbedTextWidth(Utilities.java:191).java:497)
20/1/13 12:36:59.460 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at processing.app.syntax.JEditTextArea._offsetToX(JEditTextArea.java:582):497)
20/1/13 12:36:59.460 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at processing.app.syntax.JEditTextArea.scrollTo(JEditTextArea.java:464)2):497)
20/1/13 12:36:59.460 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at processing.app.syntax.JEditTextArea.scrollToCaret(JEditTextArea.java:429)7)
20/1/13 12:36:59.460 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at processing.app.syntax.JEditTextArea.select(JEditTextArea.java:1205)a:429)7)
20/1/13 12:36:59.460 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at processing.app.Editor.setSelection(Editor.java:1616)Area.java:1205)a:429)7)
20/1/13 12:36:59.460 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at processing.app.Base.findInsertPoint(Base.java:737)6)Area.java:1205)a:429)7)
20/1/13 12:36:59.460 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at processing.app.Base.handleOpen(Base.java:922):737)6)Area.java:1205)a:429)7)
20/1/13 12:36:59.460 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at processing.app.Base.restoreSketches(Base.java:503)6)Area.java:1205)a:429)7)
20/1/13 12:36:59.460 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at processing.app.Base.<init>(Base.java:420)java:503)6)Area.java:1205)a:429)7)
20/1/13 12:36:59.460 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at processing.app.Base.main(Base.java:194)0)java:503)6)Area.java:1205)a:429)7)
20/1/13 12:36:59.461 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)va:1205)a:429)7)
20/1/13 12:36:59.461 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
20/1/13 12:36:59.461 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
20/1/13 12:36:59.461 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at java.lang.reflect.Method.invoke(Method.java:597)DelegatingMethodAccessorImpl.java:25)
20/1/13 12:36:59.461 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at apple.launcher.LaunchRunner.run(LaunchRunner.java:116)tingMethodAccessorImpl.java:25)
20/1/13 12:36:59.461 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at apple.launcher.LaunchRunner.callMain(LaunchRunner.java:51)MethodAccessorImpl.java:25)
20/1/13 12:36:59.461 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: at apple.launcher.JavaApplicationLauncher.launch(JavaApplicationLauncher.java:52)ava:25)
20/1/13 12:37:01.596 PM [0x0-0x3f03f].cc.arduino.Arduino.teensyduino: Experimental: JNI_OnLoad called.
Hope this helps! I see from some of the posts here that there is a beta11. I will give that a shot, too.