I think building a PLN is another way for teachers and students to become lifelong learners.
Using web tools like blogs, wiki, twitter, and facebook, especially at times that are convenient for you, opens up a whole new door of resources. Having a PLN gives teachers a chance to talk about professional topics together and gather insight from one another to help us learn.
From the commenting advice, I like the idea of posing a question to stimulate a response. It is a good way to encourage someone to make a comment.
I commented on the following blogs:
blogging in the classroom
11 Tools for 21st Learning@ Tiger Trail