One of my biggest issues with developing for facebook is that there are so many applications out there that dilute the platforms underlying value by using unethical practices.
Today, Facebook to a HUGE step towards correcting that. They completely redesigned their developer website to be more focused on their guiding principles.
Great social applications are meaningful as they offer users value, trustworthy when they respect users, and well-designed when they are usable and built to scale.
These changes, coupled with the new Facebook Connect are going to start driving some major changes in the Facebook Application arena.
It will be interesting to see what happens from here.