I have nothing but sympathy for David, and have great hopes that he doesn't spend jail time when he didn't intend harm. I hope that the judge and jury consider his "intent" during any trial.
Having said that, though, I did want to say that installing software on any organization's machines without permission has been, is, and will always be a foolish, if not an illegal, thing to do. Regardless of the nobility of the intent, you're still introducing something into the organization's systems that could cause problems.
In the bigger picture -- the concepts behind P2P aren't "new", but the public view of these concepts is; if we continue to bind legal behavior (or lack thereof) with P2P, actions such as David's will never be considered acceptable, and most likely will never be permissable.
If nothing else, we need to use common sense when we use technologies based on P2P -- for the technology if not for ourselves.