If Jeff's tip of booting while holding down the mouse button doesn't work, you're going to have to channel your inner McGuiver. If you slide down the faceplate to see the front of the actual drive, you may be lucky enough to find a pinhole below the disc tray. Apple use more than one optical drive model in their desktops, so you may or may not have one on yours. If you have a pinhole, stick a paper clip in there and it'll mechanically push out the tray.
If you don't have a pinhole, you may be able to see where the drive's Eject button used to be before it was ripped off to fit inside the case, on the lower right of the drive's front panel. This is usually hidden just behind the computer's case. If you see that, there may be a button stub hidden in there. I've managed to reach it with a bent paper clip when in a situation like yours and the drive opened up immediately. Some other drives I've seen in Macs still have a complete eject button. Basically, you want direct access to the drive's controls, as it's software that is preventing the drive from opening right now. Some drives have neither of these two lifesavers. In that case, you could take the drive out of the case and try to figure something else out, or take your machine down to the shop to get a CD out of the tray.
Thanks for both responses. I'll book mark this for future reference.
I got lucky. After making this post I did some other things online. Not meaning to wait on the disk I just got distracted. Then all the sudden the drive start reving like when a DVD is in it's burn mode. So instead of turning my computer off I just left it on over night. I came back in this morning and it was ejected.
I threw the disk away and all is good again.
I don't have any charming or witty things to put in my signature. So as Peter Griffen says, "That's may mama!"