I found a few of these floating around youtube.com this week. I think that they are two really good explanation's of web 2.0. The first is a more "classroom" idea, and I think that the second one really speaks out to the artistic quality that technology has allowed more people to connect with. But mainly, it just looks really cool.
These are great tools if you are still trying to think out what exactly web 2.0 means.
I really think that harnessing the power of these sort of apps, even if you are a late-comer to them, can really impact ministry and just general community.