Yes and no, it doesn't decode directly - but many obfuscated scripts work by decoding a string that contains some code (like in the OP's example), and then evaling that string. So hooking eval to print the code instead of running it actually does decode such scripts. For example, scroll down to the bottom of that forum thread you linked to earlier. I'm not sure if the OP's script uses eval, but it seems like a good guess.