I could see Facebook extending on facebook connect on this front:
For sites that had facebook connect available for login, they would be able to serve ads customized on a per-user basis - provided the underlying http ad request can include some sort of unique per-session hash, instead of being funneled through the traditional facebook connect API.
Their problem, of course, comes with attempting to monetize areas of their site which do not require a facebook connect-enabled login to continue.
I'd be frightened of this for a few reasons:
- FBC may become required - not optional - on many sites which do not currently require it. The flip side of this is it forces the sites which wish to fully monetize to actually come up with interesting and unique ways to tie into the user's social graph (in order to drive uptake of FBC as a protocol). On the other hand, it provides single sign on - which many, many users have been clamoring for (even if they didn't know it), for years.
- I dislike the FBC protocol, and wish they had gone MySpace's route with OpenSocial. It's much more sane to deal with. If the FBC protocol and widget mechanism were more sane, it would drive up adoption on many current platforms that don't currently offer it.
- This potentially has even greater security and privacy concerns than Google has ever had to deal with. This may turn out to be a good thing.