Does Mountain lion download Apple's JDK or the OpenJDK when attempting to load a Java app?
It prompts you (just tried to open Aptana). I let it install and

java -version


gives

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)