What is a Code-Signing Cert?
Code signing is a convenient way to authenticate the person who's written some code (for example, java code in a .jar file)
A code signing cert has special abilities to be accepted by Microsoft, Sun, Mozilla as code signing certificate.
But anyway, it will working nicely only if the root cert is trusted *and* if you accept to execute the code!
joke part: At least, you will know the name of the person just before you let him/her erasing all your hard disk content 