The recent Java Mac OS X 2012-006 update from Apple removes the Apple Java 6 plug-in from your Mac. The Mac OS X Install FAQ will be updated with the next 7u release, but you may find the following information useful in the meantime.
Q: I have installed Java for OS X 2012-006 and Apple Java 6 can no longer be used for applets or Web Start.How do I get it back?
A: The Java for OS X 2012-006 update from Apple uninstalls the Apple-provided Java applet plug-in from all web browsers. You can download the latest version of Java from Oracle, which has improved security, reliability
If you prefer to continue using Apple's Java 6 plug-in, you can follow the steps provided in How to re-enable the Apple-provided Java SE 6 applet plug-in and Web Start functionality.
Q: After installing Java for OS X 2012-006, can I continue to use Apple's Java 6 alongside the OS X JDK or JRE for Java 7?
A: If you want to continue to develop with Java 6 in a Terminal window you can modify the startup script for your favorite command environment. For bash, use this:
export JAVA_HOME=`/usr/libexec/java_home -v 1.6`
Some applications use /usr/bin/java to invoke Java. After installing Java for OS X 2012-006, /usr/bin/java will find the newest JDK installed, and will use that for all of the Java related command line tools in /usr/bin. You may need to modify those applications to find Java 6, or contact the developer for a newer version of the application.
Also, this update removes Apple provided Java Preferences app. For more information on how to determine the default version of Java on your system, see Determining the Installed Version of the JRE in the JRE 7 Installation for Mac OS X page.