If your interpretation was correct, then I could require Cubase to be
 GPL'd by writing a VST plugin for it and publishing it under the GPL.
 This would obviously be absurd.  In real life, a court faced with a 
 No, Steinburg wouldn't be held to the GPL... your user would. 
 
 My _user_?  That can't be the case, the GPL only covers distribution.
 Nick's interpretation was "same memory space => derived work",
 implying that a host that loads a GPL'd plugin is a derived work of
 that plugin, ergo Cubase is a derived work of my VST plugin -- which
 is obviously absurd.
 
 
Your user is the one doing the linking (via VST)... so they're the ones
making the violation.  You have to give special permission to do this: