Quite by accident I just realized that pressing Option-S auto-corrects your commands in the Terminal. Type this in the Terminal:
% defAultsNow press Option+S and the command is corrected to display:
% defaults[Editor's note: On my machine, it's the Escape-S key combination that fixes the typo, and it will only fix one wrong character per entry. So "emevs" won't be fixed, but Escape-S on "emecs" will turn it into "emacs".]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20021014051341777