Last week in Colorado a 46% scale RC plane flying a demo at a charity event at a private airfield got clipped by a full scale biplane with two people in it. Apparently, the video has been taken down from Youtube but there is a short article and a copy of the video over on Jalopnik (I have attempted to embed the video above). You should probably watch the whole video and read the article to get a sense of the event and the airfield before jumping to any immediate conclusions regarding blame.
I think this is a decent indicator of the complexities and responses you can expect when incidents like this eventually occur that involve amateur, unpiloted vehicles...the general aviation guys will say "get those toys out of our way!" and the UAV people will probably say something equally one-sided.
You guys with a lot of experience at managed RC events will probably see a lot of things that I don't see. The FAA is investigating, of course, and I imagine that there will be plenty of blame for just about everyone involved by the time the report comes out. A few feet one way and it would have been a near miss we might never have heard about and a few feet the other way would have produced multiple fatalities that might have defined the future of this hobby.