I doubt X11 will EVER be integrated in Mac OS X. X11 sucks way too much ass. Apple's implementation also has a flaw in that they use the Aqua appearance even though not a single X11 app follows the Aqua behavior.
Their browser also has interface problems, like why the hell did they use Metal?! System Preferences still lacks a way to change the file type mappings, you still have to use IE for that.
As for G4 I have yet to see a running A1 with a G4 so I wouldn't even go as far as to say we have G4s available. In fact has anybody from MAI or Eyetech or TerraSoft said anything about a working G4 prototype? I haven't.