What does a script-Tag with src AND content mean?

Question

Example from Googles +1 button:

Answer 1

If a script element has a src attribute, the content must be ignored, any other behaviour is non-conformant.

It has been suggested in blogs (as a hack) to put content in the element knowing that it won't be evaluated, then use DOM methods to get the content as a string and either eval it or insert it in a new script element. Neither of these are a good idea.