Enabling Java 7 on Mountain Lion
Apple's tools don't see Java 7, Oracle's tools don't see Java 6; it's all a bit ugly. Luckily there's an ugly fix to go with it!

Normal Mac Java 6 running on 10.8:

java -version
java version "1.6.0_33"
Java(TM) SE Runtime Environment (build 1.6.0_33-b03-424-11M3720)
Java HotSpot(TM) 64-Bit Server VM (build 20.8-b03-424, mixed mode)


Install the Java 7 JDK (not just the JRE) from Oracle.

Move the system java out of the way (so you can get it back if you want):

sudo mv /System/Library/Java/JavaVirtualMachines/1.6.0.jdk /System/Library/Java/JavaVirtualMachines/1.6.0.jdkx


Then symlink 7 in place of 6:

sudo ln -s /Library/Java/JavaVirtualMachines/jdk1.7.0_06.jdk /System/Library/Java/JavaVirtualMachines/1.6.0.jdk


and voila:

java -version
java version "1.7.0_06"
Java(TM) SE Runtime Environment (build 1.7.0_06-b24)
Java HotSpot(TM) 64-Bit Server VM (build 23.2-b09, mixed mode)


I've not had trouble with any java apps so far (apart from java preferences which checks which java it's running under).

There's probably a better way of doing this, but it works for me.