Facebook's sole function is engagement. It connects people with one another. Its $3 billion in revenue and $1 billion profit come from advertisers who believe that there must be ways for brands to profit from that engagement. They don't know how to do it yet. The two hypotheses they're testing are putting ads around it, and trying to actually host some of it via branded pages interspersed with people pages. There's no evidence that either yields much beyond nice-to-have benefit, and some experimenters (most recently GM) have given up trying, for now. Again, since Facebook makes money either way, I'd take a small piece of such failure and consider my life's work a success.

But the bet on the inherent value of engagement is still a bet, and...