I think it's a bit over 150 million users. The community is slowly growing up, but will reach a big number in a few years (probably 400-500M users). The more Bitcoin users the community gets, the more people will hear about it. Because it's like an infinite pyramid: you tell your friends about it, they tell their friends about it and so on.
I haven't seen the stats, but i assume there are millions of bitcoin addresses, which could mean we got a few 100k bitcoin users. with that i mean active bitcoin users.
Because active users is the information you would want to know.