Before anything else, this is a gorgeous plugin!
I was having the same issue on both a centos and Mac server with 3.0.3. I put the shortcode in the HTML side, and there were no smartquotes. I finally had to change the code to use boolean values, with a default of TRUE and using showkey=1 or showkey=0 to make it work.
PHP is not one of my strongest languages, so I have no idea why this would happen. I hate to have modified code, but it was my only solution after a couple of hours.
Any other ideas?