IMac only appears to respond to Cmd-Opt-P-R

Question

I have a 24" aluminium iMac from 2008. Yesterday it swallowed a DVD which made it unhappy; there's a continual (2 second or so cycle) of the drive spinning / stopping / spinning / stopping.
I tried the various procedures for ejecting the disc, (including normal methods within OS X, the command line utility and holding the mouse button on a reboot) without luck. I then tried setting bootcamp to start up the machine as windows to see if that would offer an eject method that worked. Since then, the machine just turns on, makes a chime, and stays on the white / gray screen (with the drive spin / stop in the background).
The only thing that appears to do anything at the moment is holding down Cmd-Opt-P-R on turning on the machine. Other key combinations, such as holding down Shift, or the Opt key, do not appear to do anything.
Suggestions welcome. I'm covered by applecare, but I'm (a) currently snowed in so unable to take it anywhere for a while and (b) would like to recover my data from the harddisc.

Answer 1

Do this only if all else fails. Looks like he's got double stick tape on the card that faces the label side. And if you attempt this, I'd only put the tape on the inside of the card. Somebody here tried this a few weeks ago and it worked.
http://www.youtube.com/watch?v=gkMJDOER4uM
there's a continual (2 second or so cycle) of the drive spinning / stopping / spinning / stopping.
Which drive? The optical drive?
The only thing that appears to do anything at the moment is holding down Cmd-Opt-P-R on turning on the machine. Other key combinations, such as holding down Shift, or the Opt key, do not appear to do anything.
That's a PRAM Reset. You mean that's the only thing the computer responds to? What happens after doing that?
Try doing an SMC Reset. Shutdown, remove all peripherals except the keyboard and mouse, unplug the computer, hold the power button in for five seconds, plug power back in and restart.