Quote from Pekelo:
Another thing to consider is the number of individual, fairly often users. That number is much less than the often quoted 600 million. One person can have multiple sign ups (just like here) and a fairly big number of users might use it only occasionally (just like here). Or they might not share much personal data.
I would say the number of daily (or fairly often) users is probably 1/5th of the all accounts. It is still a huge number, but considering that 2/3rd of the accounts are NOT from the USA, it can be "only" 30 million Americans.
I am not sure there is huge advertising value of users from Albania and such. They are still working on tapping the Chinese people and as it was mentioned in the CNBC Facebook special, China already has its own social networking sites...
By the way the current number what they mentioned was 1 million new sign up per week. Doesn't seem to be slowing down, just yet...