Replacing X11 with XQuartz on Mountain Lion

1. It is a bit of a surprise to realize that X11 is missing from your system after an upgrade to Mountain Lion. Apple does a good job of pointing the user to XQuartz but something critical is lacking!
2. Apparently the installation (X11 2.7.2 - 2012.06.01 - First release supported on Mountain Lion) needs to be run twice in order for it to be successful.
3. The first time it asks for a system restart after which the programs which are supposed to pick-up on and start using it are still asking dumb question like "Where is X11?"
4. If you run the installation a second time though, it will now place an app called XQuartz in your system and you can launch it from Spotlight.
5. Afterwards, you are no longer asked the question: "Where is X11?" ... the dependent applications simply work :)