"We changed the social graph from being an abstract concept to a social movement."
The social graph to which he referred is the network of family, friends, co-workers and casual associates in people's lives.
Facebook sees its role as using Internet technology to let people easily share personal information how and with whom they wish.
Last year, Facebook freed third-party developers to created hip, fun and functional applications that website members can put in profile pages.
"The last year has been pretty crazy," Zuckerberg said. "The results show that a lot of people all over the world are joining this movement and doing it using the applications we all built in this room."
The number of Facebook users has grown to 90 million people from 24 million people in the past year, Zuckerberg sad.
MySpace remains the most popular social-networking website with Facebook in second place but closing the gap, according to figures from industry-tracker Hitwise.
A multi-billion-dollar "ecosystem" has grown up around Facebook, with custom application creators including Zynga, Flixster and LivingSocial recently winning millions of dollars in funding from venture capitalists.
Zuckerberg humbly told the gathering that Facebook plans to work more closely with outside developers.
"We've made a lot of mistakes and there is a lot we have to learn," Zuckerberg said.
"We haven't done enough to reward the good citizens in our ecosystem and, on the flip side; we haven't done enough to punish the applications that have been abusive."
Facebook this week rolled out revamped profile pages and will launch a "Great Apps" program to give priority to programs that are "meaningful, trustworthy, and well designed."
Facebook has been expanding internationally and announced third-party developers can use its translation program to match languages to the those used everywhere the social-networking site is available.
Digg, Moveable Type and City Search have adapted their websites to connect with Facebook, and a software kit was made available on Wednesday.