Each time I've seen the Facebook honchos live on stage, they left me with a bitter taste, confirming that they can't be trusted with personal information.
Now one may wonder how committed FB is towards third-party developers:
Nobody knows how committed Facebook is to improving the platform or the role applications are meant to play in the overall Facebook ecosystem. Signals like the reduced level of direct participation in the developer community, increasingly restrictive developer policies, and the Facebook profile redesign seem to indicate that they are trying to regain control over some, if not all, aspects of application development while maintaining an aloof demeanor towards developers.
It boils down to this: investing most of your man-hours into Facebook at this point in time is a mistake. The potential return on that investment, a year after launch, is a fraction of what it once was. And the fact that Facebook continues to change the rules and selectively break them for their own benefit means the risk is comparatively higher.
Also when Jessy writes that "Facebook was willing to hurt independent developers when it benefitted them", I'd say that with Beacon, they've shown that they are equally willing to hurt their users for a quick buck.