Respected Twitter poster saying that FB will be added to Russell 1000 on June 22, to the tune of 15MM shares. He said it's official per his tweet, but I have yet to confirm via an article online.
Marc Lehman @markflowchatter
It's official $FB selected for the Russell 1000 add .As I said earlier today, it will take place on June 22nd, 15M or so shares to be added
ED:
http://www.bloomberg.com/news/2012-06-08/facebook-may-join-russell-indexes-amid-smallest-revamp-since-04.html
10 AM today (predates above tweet)
Facebook, the world’s largest social-networking company that raised $16 billion last month, will join the Russell 1000, according to BlackRock Inc., Credit Suisse, Investment Technology Group Inc. and Macquarie Group Ltd. The stock, which has sunk 31 percent since its debut, would account for 0.08 percent of the rebalanced Russell 1000, resulting in buying of 13.5 million shares, Macquarie estimates.