Facebook, as you are probably aware, allows users to post a "status" -- basically a brief note about what you're currently doing or thinking. (It's like an internal version of Twitter.) The Facebook program for the iPhone defaults to a list of recent status updates by your friends, so checking it has become an easy way for me to zap any random moment of boredom in my day.
I have about 250 friends on Facebook. I know them from lots of different settings, and am in touch with them in the real world to wildly varying degrees. There are people I see all the time, and people from high school who I didn't really know that well back then and haven't talked to since. Yet I have what-I'm-doing-right-now updates from the cross-section of friends who post status updates.
It's quite fascinating to get (sort of) reacquainted with people via bulletins about the minutiae of their daily lives. If I were to run into someone in the grocery store while visiting home, the conversation would run along the lines of where they're living now, where they work, etc. On Facebook, I know that they've got the flu, had Chinese food for dinner, are driving to Boston, or whatever. (Basic biographic data is available, too, but I don't look at profiles on a daily basis.) Normally, when you have this sort of information about a person, you know them pretty well and have the broader context of their life to fit it into, but on Facebook you may only have these bits. It's a strange way to know someone, though a surprising amount can be gleaned by what they're doing, what they choose to post about, and how they say things. It's also interesting to see how my range of acquaintances react to the same things, like the stock market plummeting (once day three different people made reference to putting money in their mattresses) or the presidential campaign.
Anyway, I've got jury duty tomorrow, during which I'll certainly have plenty of time to check Facebook status updates...