If you have a stunning idea, what's the best way to find the right group within Google to share it with....? Do they have a message board with key words where they can share ideas and collaborate on projects?

Simon, have a look:

http://blogoscoped.com/archive/2008-03-12-n39.html#googleIdeas

Or try this: http://cangooglehearme.com/chapter1.php :-D