Thanks to Steve Hargadon on the Classroom2.0 ning. He posted a link to this great video that I think does a wonderful job of quickly explaining what Creative Commons is and how it came about.
This would be a good intro for teacher PD. Only problem that I see is that in our district, all social media sites like youtube, flickr, photobucket, etc. are blocked for students. Teachers can now access them though, so for photos, flickrstorm would be a good option to share with them as well.
Here's the video to share: