I have just recently began using twitter to build my PLN. I love it, it is so fantastic to be connected to smart, motivated people. It is humbling that so many people are willing to share what they know and they find. I am going to introduce the idea to my class and I think it will benefit them immensely. One of our classroom goals is to build a learning network on-line and twitter will be a big part of this.
I found two posts (on twitter, there will be many) that may be helpful to other teachers breaking the same ground as me. One is The Ultimate Twitter Guide for Teachers from the blog Edudemic. It has many links and is an ample resource that you need to bookmark and share.
The other one is "5 Twitter Uses for School Leaders", from the blog Leaders On Line. This post gives five foundations for effective twitter use that is very helpful in guiding educator use and convincing staff to get on board.
Enjoy the resources!