Twitter celebrated its 5th year of existence by listing a number of stats. It took 3 years, 2 months and a day from the first Tweet in 21 March 2006 to the billionth. It now takes users one week to send a billion Tweets.
The number of new Twitter accounts created on 12 March this year, was 572,000, while over the last month the average daily number of new accounts was 460,000, and mobile users have increased by 182% over the past year.
As of last reporting, twitter has only 400 employees, up from 8 at its inception.