Got this notice today. I did see this yesterday but I was able to resolve it. The problem seems to be that the OSX update turns off the enable applet plug-in and Web Start applications checkbox in the Java Preferences application. This causes the admin start app to come in as a text file and no way to open it.
All I did was open the preferences application. Check the box and check the two Java SE 6 apps 54 and 32 bit.
That broought my icon back to the proper look and opens the login just fine.
No need to downlad Java 7 and get a whole new set of issues.