In case you’re not a fan of the delayed eject functionality that 10.4.9 brings to your system, here’s a quick tip on getting around it.
If you want to eject your disc, and not be bothered to wait, hit the Eject key, and then quickly follow it by pressing the CMD + Option keys. You’ll get your disc back quickly, just as you used to.
I personally don’t mind the delay (now that I know how to get around it) as I’ve accidently ejected discs before, that I didn’t want to.
You can find this tip and many more over at MacOSXHints.com