Twitter can be used as tool to keep up with your profession. Many people use it to follow other professionals' tweets about their chosen field. You can search for people that you have read about in the professional literature or search on a #common term to see if anyone has posted the topic. Others use it to toss out an idea and get instant feedback.
Be aware, although people do use Twitter to promote themselves professionally, they may also include personal comments. Also, sometimes it can be hard to filter through all the information. One good method to sort through everything is to save relevant searches. If you do a search on #educational_technology or #educationaltechnology or #edtech and find that many of the tweets are producing good information, then save the search and refer back to it.
Remember, Twitter is a 2-way street. Tweet your professional accomplishments, ideas, and failures. Get people to follow you and gain recognition. Also it's fun to follow the back-channel comments at conferences :).