As Facebook and Twitter both continue to evolve into similar offerings with similar services, one major philosophical difference between the two social networking behemoths seems to have no chance of disappearing any time soon: a focus or lack thereof on privacy.
Facebook seems to be obsessed with perfecting its privacy policies. Numerous iterations of their privacy functions have been rolled out since Facebook launched. The most fundamental and controversial change involved opening the website to non-college/high school students - to everyone. Today Facebook has again announced new modifications - slowly starting to open up its website. This issue isn't going away for Facebook; it's only becoming more muddied.
On the other hand, Twitter has reached massive scale with very little regard for privacy. Any user can follow any other user. Although the "block" function exists, I suspect that it's mainly used to block spammers and other evil-doers. Very low expectations have been set.
What does this philosophical difference mean? I think it's clear that Facebook has to play catch-up with Twitter on this issue. As more and more people become comfortable with the Internet and the free communication that it allows, privacy is quickly losing its value. Facebook should stop wasting time and other resources on this matter. Facebook needs to realize that privacy is not a requirement but instead an obstacle.