While editing and testing this hint, I was intrigued to find that Keynote, despite having a capitalization plist file buried in its application bundle, didn't seem to use that file at all. On my two machines, no capitalization replacement took place in text fields, so it seemed the file was there for no good reason. And after digging through the Inspector, application preferences, and the manual, I couldn't find any GUI method of enabling capitalization fixes. The referenced hint, however, seems to imply that this does work for some Keynote 3 users. So the following is for those of us who don't have capitalization fixes in Keynote 3 and would like them...
To enable this feature, make sure Keynote isn't running, then open Terminal and type this command:
defaults write com.apple.iWork.Keynote kSFWPFixCapitalizationProperty 1
Launch Keynote, and you'll find that iwork will now become iWork, and may will become May, etc. (Use the referenced hint to modify which words are capitalized.) If you ever tire of the automatic corrections, quit Keynote and re-run the above command, but replace the 1 with a 0 (zero).
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060414072655763