How to install java jdk 7 on Snow Leopard

Use Pacifist from http://www.charlessoft.com/ to open and install the 'JDK 7 Update X.pkg' in the 'jdk7-7uX-macosx-x64.dmg' file you download from http://www.oracle.com/technetwork/java/javase/downloads/index.html

From what I have read JDK 7 does not require 10.7+ so I simply opened the shipped .pkg installer file with PackageMaker (an Xcode tool) and removed the OS version requirement and re-built it.

You will need to copy the installer out of the .dmg file since you have to save changes.
Edit: You will need to Build to another directory as the mounted .dmg is read-only.

So far in my using this I haven't experienced any issues, even the Java preference pane is working properly.

One thing to note, you will have to reorder JDKs in Java Preferences.app to get programs to use the new JDK instead of Java 6.

I've even gone as far as to copy the Java 7 .jdk bundle into /System/Library/Java/JavaVirtualMachines/, and it seems to be function normally.

Just don't move/rename the JDK bundles while Java applications are running; not that I've done that by accident or anything...