Growing like a weed. Racing like a comet. There are a lot of ways one might describe the trajectory of the Google+ social network, which launched to limited field testing June 28 and has been opening and closing its access ever since.
What is hard to do is nail down a user number for long. Two days after Ancestry.com founder Paul Allen used Google+ surnames to estimate that the service was fast-approaching the 5 million user mark, Allen said his latest data shows that the number of Google+ users worldwide reached 7.3 million July 10, up from 1.7 million users on July 4. That is a 350 percent increase in six days.
Moreover, Allen calculated user growth at midday Monday, July 11, to that night and found that there were 9.5 million users, which means some 2.2 million people joined Google+ in less than 36 hours.
One reason for this new influx is the Google+ invite button, which Google re-enabled July 10.
Noting that the user base is "growing so quickly that it is challenging for me to keep up," Allen said that Google will easily pass 10 million users July 12 and could reach 20 million user by this coming weekend if Google keeps the Invite button available.
For those curious about Allen's methodology, he used the U.S. Census Bureau data about surname popularity in the U.S. -- certainly a reliable metric -- and compared it to the number of Google+ users with each surname.
He then I split the U.S. users from the non-U.S. users. By using a sample of 100 to 200 surnames, he could estimate the total percentage of the U.S. population that has signed up for Google+.
Allen then used that number and a calculated ratio of U.S. to non-U.S. users (1 U.S. user for every 2.12 non-U.S. users) to generate worldwide estimates. Allen acknowledges this may not be the soundest of global user estimates outside the U.S.
Still, it's clear that Google+ is growing mightily, however you want to describe it. How long can Google keep up this growth? That's a great question.
My guess is, unless Google+ begins to drag from user fatigue and early adopters start flaming it, Google+ could be the most viral social service the world has seen. More viral than, yes, Facebook.
Why do I think this? Google has such a strong brand. Everyone knows it and when Google puts out a solid or intriguing product, it tends to get used loyally by Google fans and early adopters, with general consumer masses glomming on later.
Of course, we need to curb this enthusiasm with the idea that Facebook has 750 million users, many of whom won't feel they need to build out another social graph of friends with whom to share content they can already share on Facebook.
That's Google+'s biggest impediment to massive growth right now.