Users who have installed the recent OS 10.4.9 update have probably noticed that it introduced a delay between the time the Eject key is pressed and when the eject function is activated. This delay also carries over to the Control-Eject shortcut for bringing up the Shutdown dialogue. Whereas a delay might be useful in preventing accidental presses of the Eject key, the Control-Eject combination is far less likely to be pressed accidentally, so the delay is a bit of a nuisance.
Fortunately, the shutdown dialogue can be summoned quickly without waiting for the delay. Instead of using the usual simultaneous Control-Eject combination, use Eject-Control. That is, press and hold the Eject key first, and then quickly (before an eject is triggered) press Control.
And if you'd like an immediate eject action, use Eject-Option in the same manner as above. The same seems to apply when you wish to sleep the machine immediately; use Eject and then Command-Option.
I suppose I should be grateful that the option of bypassing the delay is there, but I'm not sure I like the complexity of key combinations where the order in which the keys are pressed matters. I see no reason why the usual convention of a simultaneous (or modifier-first) Control-Eject, Option-Eject or Command-Option-Eject couldn't be used for their respective functions, given how unlikely it is to accidentally press those combinations.
[robg adds: These revised shortcuts work as described on my MacBook Pro. On my Mac Pro, however, I can't access the instant-eject feature -- I think that's because I have a second DVD-R in the machine, and Option-Eject is reserved to open that second drive.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20070316233431364