Experience - loads of poker sites have had data security breaches. I can't recall hearing of one on facebook that wasn't user side (correct me if I'm wrong).
Motivation - There's a big issue online with identification and authentication, sites want to know who they're dealing with and people want their details to be secure. Passwords just don't cut it any more... Given that there's a big opportunity for facebook (and others) to provide that service. Also loads of people ready to step up and take FB's social networking crown off them too (Google for one...) - if people lose trust in facebook's security it would be very damaging to their bottom line.
Poker sites, I'm not so sure, I think they'd be bothered, but not as much as facebook. Nothing would really surprise me any more though...
Talent - facebook has loads of talented engineers working on things like security (by that I mean keeping user data secure, identification etc), I doubt the poker sites can attract the same sort of talent or that the people they use they people they have (as much) to that end.
Abstraction is the right term (for what I think you mean), but I doubt it has much benefit here.
As to the deal I'd reckon it's a small thing for facebook and a big deal for the poker sites so the deal would be on FB's terms (see spotify). If I was FB I'd want as much control as possible - accounts funds etc - and just leave the running of the games to the poker site with a rake split. I wouldn't want to let people on the provider's software play against FB players - the grinders would multi table and get more money that way (I might be wrong? FB might not have the knowledge to demand that, although I'd imagine they'd want to force everyone to play through FB so they can get a cut).
Iron -wasn't Yahoo limit poker and before the explosion?
i really want to respond to this post in a lot of detail because it raises some really interesting points about what fb's perfect positioning in the market should be.
get ready from some tl;dr that is hopefully v interesting in the next couple of hours -- just need to finish a little something first
