EVERYONE seems to be viewing this as a showdown between Google-&-Friends and Facebook (and Microsoft).
- Facebook is a network of users. People are on Facebook because their friends are on Facebook.
- Open Social is a developer platform.
Users don't join social networks for widgets, they join them to socialize. Users follow their friends.
Widgets are not a compelling reason to join a social network. Most Facebook users aren't using all but a handful of the most popular apps. Why would they join another network to get access to more apps/widgets they don't care about?
Open Social is a marketer/developer play. Open Social offers marketers and developers easy access to multiple networks via a single platform. It's a long tail play.
However, if marketers and developers want to play where the people are, if marketers want to hit the richness of that fat belly higher up the long tail then they will continue to develop Facebook Apps.
The Open Social play created a compelling option for marketer activation of alternative social networks.
Open Social will not affect Facebook in any meaningful way for the foreseeable future.