Found on @ttunguz's blog:

Zuck proudly proclaimed that Instagram has passed 100 million users.

Instagram passed 80 million users in July, so its user growth has been stunning.

ComScore reported a week ago that Instagram’s website is the 56th most popular site in the U.S., with 22.7 million monthly unique visitors.

Acquisition price aside, the fact that 13 people can grow a service to 100 million users in under 2 years and frighten a massive company like Facebook says a lot about our industry.

Also, brace yourself. Facebook will soon be dominated by Instagram photos.