Would it be possible to provide this as an option in each user's profile? It's virtually impossible to talk about regular expressions with smilies on, but every so often I forget to turn them off before posting. Then I edit the post, turn off smilies and resubmit it, only to find that extra spaces have been inserted around the offending characters, and I have to edit it again.
Come to think of it, why do smilies even work inside CODE tags?