It took CityVille 8 days to reach 6m players (updated)

"Zynga’s newest game, CityVille, is the fastest growing game in the company’s history. But we already knew that. It had nearly 300,000 players in the first 24 hours, and 3 million daily active users in its first week.
But it’s growth ramp keeps on going crazy. Now, not quite two days after it hit the 3-million user mark, it is already at 6 million daily active users, we’ve learned from the company. To put that in perspective, that is four times faster than it took FrontierVille to get to 6 million daily active users, and more than five time faster than it took FarmVille.
Time It Took To Get To 6 Million Daily Active Users
FarmVille: 46 days
FrontierVille: 32 days
CityVille: 8 days"
Source:  Techcrunch, 11th December 2010
Update - 22m in 11 days