I've found that my use of social media is evolving. I sign on to Facebook when I have time to kill, and I've sorted my friends into lists of varying lengths so I can check in on specific groups of people. It's an ideal venue to post and enjoy pictures, but I find that the preponderance of political posts frequently annoys me even when I agree with the core sentiment.
Twitter, however, intrigues me more and more. I love the idea of it being archived by the Library of Congress, so that future historians will have a trove to explore and fill the void left by the decline of physical letters and diaries. I fear that future generations will see the past few decades as a lost era, with few personal primary documents between 1980 and 2010.
Twitter also uses a lot less data to explore, which is important since my data connection is frequently subpar: my choice of carriers has to do with international and cost factors rather than with signal strength. I've also found it much easier to avoid political debates unless I specifically go looking for them, which is useful.
To sum up, I use Facebook to broadcast the outlines of what I'm doing and thinking, as well as to check in on friends. Livejournal remains my preferred venue for more long-form ideas, even if only a paragraph or two, but I'm spending more and more of my time engaging via tweet.
And things are slowly settling into place, at least for the nonce.