yeah dude, i had same prob in r33 gtst. Went to do burnout with some mates in the car, revved, dumped clutch and car didn't move at all just revved like shit. Went to put clutch in and realised it was still stuck all the way down. Same thing, just popped out after a few secs and smelled like shit. Clutch then started taking heaps far out. That was a few months ago and i've been nice to it since. Still i think the clutch is gone and probably a hydraulic problem.
Let us know what yours turns out to be man
Cheers