I have one of the early iMac "bondi blue" keyboards that I use for the mini and the iMac. Good because it is compact (I don't like table-sized keyboards aka AEK-II) bad because it's missing keys. As it lacks an Eject key, I had a slight problem with yes, the CD drive on the iMac. Turns out, hidden in the 9.2.2 installation disk is an Eject applet (and a Control Strip module) so that the F12 key ejects the tray, or it can be manually changed in the Keyboard preferences, as it is assigned like a program-launch button. 10.2 recognizes F12 as eject so that's not a problem.

When I had the iMac apart, I peered into the DVD drive, and didn't see anything overtly suggesting a manual eject button. Pffft. I do have a spare Kensington around for this very reason which has an Eject key (and a Del key, which I am lacking for when I'm in XP on the mini...) and all the sound buttons. Never know when you might need it.