I've always been comfortable with using the end of a smiley as a closed parenthesis. What I really despise, though, is the advent of software that turns your ascii smilies into graphical equivalents without being asked to.
So you type something perfectly sensible, and the bastard software turns it into:
One of the funniest things with xkcd is the alt text (hover your mouse over the comic) - It's kind of like the second punch line. That's why I've been linking all the ones I post back to the original page on xkcd.com. IIRC, the alt text on the above one was something about describing the International Astronomical Union's president's mother as planetary in size...