*What* is the purpose of the GPL?
*Why* does the Free Software Foundation try to *convince* people to use the GPL?
The GPL is an ETHICAL license... the reason why there is an Open Source movement is because some people don't like the ETHICAL elements of the GPL. When you comply with the terms of the GPL, you are complying with an ETHICAL stance on software development and how the software development community should function.
So yes, Conrad, the *letter* of the license should be sufficient, especially considering the *intent* of that license.