I don't think Microsoft paid the 240m$ just to have some shares in facebook. The most important thing Microsoft got out of the deal was the international adver

I don't think Microsoft paid the 240m$ just to have some shares in facebook. The most important thing Microsoft got out of the deal was the international advertising exclusivity on Facebook. And that could only go away if Facebook starts losing page views and eventually become irrelevant. Opensocial is probably a move forward and might eventually cause facebook to join and eventually break the walls, but it wont necessarily mean that facebook will lose the fight, they could still be a huge platform, maybe the biggest one (not considering OpenSocial, and looking at independent platforms, such as Myspace, Hi5 ...) and facebook could still be a popular destination for the years to come.