Speaking of Online Presence/Identity as a Teacher... an interesting article about collaboration through Twitter within the Educational Field. Includes groups that may be of interest for you to join, a list of Twitter hashtags in Education, and profiles of Educators you might want to follow.
Your personal or professional learning network (PLN) is alive and seemingly awake 24-7 when it comes to Twitter. You've probably faced a few scenarios where your real-world obligations got in the way of a hashtag chat, your vacation meant you weren't able to connect as often, etc.