If you look at DataPortability.org, it's obvious they have an explanation problem. I'm not likely their target audience, but "Turnkey Reference Blueprints" don't exactly make me want to get involved.
That's why I like this video by Smash Cut Media - it focuses on the pain of having to keep up with data across mutiple web sites - and how the Data Portability workgroup is helping to solve the problem. It's a bit flashy, but effective and fun to watch.
Check it out: