Security consultants Sophos polled 1,000 people to see what they thought about Facebook and security, and found that 95% people thought the social networking service should follow Apple's approach with the App Store and security-check all 3rd party apps running on the site. A 'walled garden', if you'll.
"Apple's developer approval process means that all code is reviewed before it's place in the App Store - this doesn't just stop yet-another fart app, it also reduces the opportunities for malicious hackers to spread dangerous code via this route. Whatever Apple is doing, it seems to be doing it right.
Now, let's look at Facebook.
Facebook doesn't check the apps you write for its platform to see if they might be malicious. That's why it's not unusual to see rogue apps spreading their spam and dangerous links across the social network."