Google+ has attracted over 43 million users since opening the doors to their new social network less than three months ago. co-founder and self-proclaimed Google+ unofficial statistician Paul Allen (no relation to the Microsoft co-founder by the same name) estimates that the social network is slowly approaching 50 million users.

Google announced nine new Google+ features last week, bringing the total number of key features to 100. The most important of them was number 100: anyone can now sign up for the social network, which was previously invite-only.

According to Allen, new members flocked to the service over the 48 hour period before posting his latest estimates which resulted in substantial growth. As of late last week, his calculations indicate that there are 43.3 million users on Google+, a number that is likely closer to 50 million as of writing.

Allen notes that the timing for Google+ opening up to everyone wasn't random. Google knew that Facebook was holding their annual f8 developer conference two days later and was likely looking to steal some of their thunder (and users) prior to the event. As he points out and anyone with multiple friends on Facebook can tell you, many people dislike the new UI changes that the complany implemented just before f8. Google's layout is much more simplistic and will likely win over new members on that fact alone.

Rapid growth is promising for Google+ as CNET reported on September 1 that weekly visits to the social networking site were on the decline since mid July.