Twitter is a much misunderstood micro blogging facility. The London School of Economics and Political Science has an excellent guide to use twitter for searching, networking and establishing a digital presence. The whole site1 is well worth a browse. It offers good advice around many of the issues experienced and beginner researchers in the social sciences face.
Once you've sorted out how to use twitter, i.e. set up an account, you'll find the #PhDchat worth keeping an eye on. You'll also discover that good folk like the thesis whisperer (@thesiswhisperer)2 is an avid user.
The hashtag, # is an important means of making good use of twitter. Patrick Powers has an excellent piece on the art and science of hashtag strategy.
Here are some hashtags that are currently popular with social science PhD folk and PhD folk generally: #PhDchat, #PhDForum, #socphd3
There is a gentle introduction to twitter for the apprehensive academic that is well worth a thoughtful read. Another useful blog post about the academic benefits of twitter can be found here.
Twitter can be used a little like Google alerts, i.e. you can scan for a phrase or name or a current conference. You can think of the people you follow as your unpaid research assistants. Simply following a debate4 will give you a good sense of aspects of the intellectual climate in which yo are interested. Don't be discouraged if your supervisor sees these things as silly and frivolous. There are many academics, particularly in education who have remained stubborn and uninformed about the growing value and role of all things digital to academic life and work.
There are a variety of ways you can use Twitter, including on tablets and smart phones. TweetDeck is a useful browser plug in or standalone piece of software that some find useful. There are many applications for making use of twitter and there is no shortage of advice to be found about what is good for what.