[noste]

While it doesn't invalidate your general point, Twitter has 600+ employees: http://blog.twitter.com/2011/08/your-world-more-connected.ht...

[UniIsland]

update on the numbers, i just searched google and found that sina weibo recruited 1000+ people in march 2011. i was being a little bit too conservative in the first place. cant really estimate how many they've employed since then.