Bebo (which is already aligned with OpenSocial) decide to clone the Facebook API too so Facebook apps will run on it.
Dave Winer says that FB supporting this effort is the "end" of OpenSocial.
He may be right, and that's a bad thing.
You can see an allegorical image of Facebook with a devil on one shoulder and and angel on the other, whispering advice in its ear. Facebook could choose to be "good" or choose to be "evil". Opening its API was good, Beacon is evil.
"Good Facebook" would be competing as infrastructure for social applications, providing more ways to let applications writers help you benefit from your social network. "Evil Facebook" thinks applications are merely a complement. It competes on "owning your social network" and reselling it for its own benefit.
While it's not actually evil to allow Bebo to clone the API. Being too blasé may demonstrates that FB are only really thinking about the dark-side strategy. Same problem is true of OpenSocial. If social-application hosting is seen as a commodity, YASNS have to compete on exploitation of your social data.