Trademark law is different from copyright law.

With trademarks you do have to defend them: http://en.wikipedia.org/wiki/Trademark#Maintaining_trademark...

However with copyrights they are yours from the moment you write something down to 70 years after you are dead: http://en.wikipedia.org/wiki/Copyright#Obtaining_and_enforci...

(And the way things are going, that 70 year number will go up by 10 years every 10 years.)

Thanks for clarifying that. I'm not really sure why I said copyright as I know better than that, I must have been tired or not thinking straight.