Why is blogging a 21st century tool?  Give one example how you can use this tool as a 21st century teacher or leader?

Blogging is a 21st century tool because people can share their thoughts and the resources they have with ease and get feedback from people far and wide.
One way I can use this tool is to create a blog where I talk about the technology classes I teach.  I could talk about what we have done, what is in the works, things I am considering and researching, things I want to know more about, and post my reflections.  I think the feedback you can get is a powerful tool for learning, getting information, and generating ideas.