I ran Oracle's Java 8 installer, and the files look like they ended up at /Library/Java/JavaVirtualMachines/jdk1.8.0_05.jdkīut previous versions are at /System/Library/Java/JavaFrameworks/jdk1.6. I'm using IntelliJ 13 CE and Mac OS X 9 Mavericks.
I want to do some programming with the latest JavaFX, which requires Java 8. Editors note: This question was asked in 2014, and the answers may be outdated.