A quick way to answer a prompt that comes up is to press the first letter of the word on the button you would be clicking.
So for the following prompt, I would type C for Cancel and Y for Yes.
This doesn’t seem to work all of the time on all prompts. However, if the selected button is the button you want, you can also hit enter to submit it. You can also use the escape key to cancel out of prompts with a cancel button.
[Submitted By Jay Ryan]

Robert
kev
the fuctionality you're talking about sounds like windows August 17th, 2005 at 6:22 pm
Andy
encro
Don't Save is Command-D
The Pulsing Button is always selected by pressing Return (Enter)
as the previous comment states you can Tab thru the buttons and the space to toggle the buttons state once you have turned on Full Keyboard Access in system preferences. August 18th, 2005 at 10:53 am
JoshB
Also, this window is where you can set keyboard shortcuts to use in all of your programs. For instance, I have Command-shift-z mapped to the 'Zoom' command, so I can make iTunes go from the full window to the small window without using my mouse. August 18th, 2005 at 11:04 am
kev
why isn't full keyboard access on by default? is there a reason to make a limited and a full access instead of just making it full? August 18th, 2005 at 1:39 pm
kev
and spacebar to act as an enter key to select either option is also not working.... is there some other option i need to change in prefs?? geez...
(im a new mac user, if that isnt obvious already) August 18th, 2005 at 1:41 pm