I've just discovered an interesting little tidbit. It turns out that Apple didn't eliminate the F12-eject key functionality on non-Apple keyboards; they just made it more intelligent. So, instead of quickly pressing F12, press and hold it for a second. Your tray should pop out and in on your command.
[Editor's note: I thought we had run this hint before, but I couldn't find it in a search of the archives. There's a hint about the F12 eject key, but it was written before the nicer delayed functionality was introduced. The comments written there regarding ejecting all mounted drives, however, may still apply.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020520084912715