Installing Java on Mac OS X used to be a breeze. Once upon a time it was part of the regular Apple update but at some point in midst Java 6 it stopped being supported and now if you want Java 7 you would need to build the jdk first to get the precious binaries.
If you are after only the binaries I found this place where they are made available. Completing the installation is a matter of drag-and-drop and finally jdk 7 will reside in /Library/Java/JavaVirtualMachines/1.7.0.jdk/.
Don’t forget to create/update environment variables or point to that location from your Eclipse, IntelliJ or other IDE. As far as I have checked, Eclipse Indigo 3.7.1 is supporting Java 7 on the fly syntax checker as part of its updated JDT. Older versions of Indigo wouldn’t recognise ie. project coin changes.