Motivated by a recent blog post on Mobile Inc, I decided to leverage some readily available data from Facebook to get a rough indication of which mobile operating systems were most popular in my social graph. What the chart above represents is a breakdown of the Facebook App installs completed by my Facebook friends, as a percentage, for the various mobile operating systems for which an app is available. The actual number of installs is a bit higher than the number of friends I have because many have multiple handsets... or have recently transitioned handsets (the old install still gets counted). Of course, what this doesn't capture are all those good folks who access the site through the mobile website or the full website (which I often do, frankly) from their phones... which presumably includes all my friends who are Nokia devotees. I'd love to hear some feedback to learn how many of you fall into this category and to learn what your social graph breakdown looks like.