No meu sistema (10.9.2), os novos JDKs estão instalados em /Library/Java/JavaVirtualMachines/
$ ls -l /Library/Java/JavaVirtualMachines
total 0
drwxr-xr-x 3 root wheel 102 10 Apr 00:51 jdk1.7.0_51.jdk
drwxr-xr-x 3 root wheel 102 10 Apr 00:58 jdk1.8.0.jdk
No entanto, o binário padrão java
ainda vem de /usr/bin
oxygen:~ user$ which java
/usr/bin/java
oxygen:~ user$ ls -l 'which java'
lrwxr-xr-x 1 root wheel 74 11 Nov 11:02 /usr/bin/java -> /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java