I would say that you are no longer a script kiddie when other people stop calling you a script kiddie. Being unable to code an exploit should have nothing to do with it. Please, if you know of every exploit that exists, and can code every exploit that exists, speak up now....

No one?

My point there is that they may not be able to code the exploit due to lack of understanding of the OS. Their coding skills may be up to par, but their other skills may be lagging. I think I'll redefine my idea of a script kiddie:

Script Kiddie: One who thinks it is cool to use, or thinks he's l33t because he uses other people's programs. (i.e. D00d! I t0t411y 0wn3d d4t s3rv3r with my IIS script. Ph33r!)