The reason I think parrot-compilers would be useful, is that its dedicated to helping people (like me) write compilers for parrot, whereas (in my understanding), perl6-internals@ is really about the development of the vm itself (I would subscribe to both). I see parrot-compilers@ as opening up more questions from people struggling with the current apis than perl6-internals@ - at least I'll post more. :)
Okay, fair enough--I could see how currently people might think compiler-development questions are off-topic.
JEff