JUST GO
i've come to observe that good ideas have a very short lifespan to work out.
you might have someone stay behind to ask questions after you give a presentation, have someone approach you after reading a whitepaper, have someone respond to an online posting, etc.. in all cases, though, it seems as though there's a very short amount of time to actually do something with that attention.
if you wait too long, don't follow up, or spend your time asking for permission you're going to lose that person and your idea isn't going to spread. don't ask permission: JUST GO (and apologize later)