As much as I like the fact that facebook provides a bunch of free services this is simply bait and switch. Turn a social networking site into a marketing panel.

Besides that, using facebook as a 'panel' seriously degrades the value of the company as a whole, panels are commodities and are definitely not valued in the 10's of billions, even the very large ones.

There are lots of players in that segment and most of them were put together with the express purpose of being used as panels, it's quite easy to get access to panels with large numbers of respondents in a given target demographic.

That's especially hard when your demographic is working single moms from Nebraska or something equally arcane, if your database isn't set up to record such information right from day 1 then you're not going to add it afterwards in an easy way.

And those respondents are usually paid for their work, fb will do the opposite, nag you and charge you to opt-out.

Of course facebook will have to turn a buck but I highly doubt this is the way to make it happen.