OpenSocial vs MS Facebook

This is going to be interesting (or at least I am really hoping that it is). Google's OpenSocial effort is clearly a reaction to the dominance of Facebook and I can say that I am relieved. The idea of one dominant social networking site is frightening. Why?
Social Networking Site Monopoly + MS = very bad tech: just imagine what a cruel hacker could do inside the Facebook world. Why should we expect this to be different. It's not trivial.
Plus, if all the social networking data is accruing at one site kiss your anonymity good bye! You maybe a digital exhibitionist but your mom may not be. By triangulating data with social ties BAM! we know a lot about your very private mother.
Also, I would prefer to keep my professional networks a la LinkedIn and my personal networks within Facebook separate. With one social networking site will you have a choice? Even though Facebook has been improving and increasing the privacy controls for individuals, the problem is that I have ties to people who have different privacy settings. Therefore I am exposed when I have no choice in the matter. For example, I am not a fan of photos of me on the internet. Yet, my friends like label their pictures of me on Facebook. I can do nothing about this. So my employer may have the opportunity to see me in a not so flattering or particularly professional light.
Facebook has no means or no real incentive to tamp down the issues that arise when you leave the atomistic world of individuals on the internet and join a social networked web.
With two players the outcome is a lot less clear. Who will reign? Will it be just one site? Or multiple? Although I know Google's OpenSocial effort is not altruistic, I am glad that it has emerged.
Internet you are nobody's bitch!