Google+, the newest social networking stream on the planet, according to a research, has already reached 10 million users mark. But, can it pass the 20 million users hurdle by this weekend?

Google+ has been here for just two weeks and already it has seen popularity that even the Google boss didn’t expect or predict. Google’s newest social networking venture, however, experienced a setback when the company failed to allocate enough disk space and started spamming users.

The company re-opened the social network to the masses last Thursday and Vic Gundotra, Senior Vice-President of Social for Google was apologetic for the company’s previous policies.

Please accept our apologies for the spam we caused this afternoon, Gundotra wrote on his Google+ wall on Saturday evening. “For about 80 minutes we ran out of disk space on the service that keeps track of notifications. Hence, our system continued to try sending notifications. Over, and over again. Yikes. We didn't expect to hit these high thresholds so quickly, but we should have. Thank you for helping us during this field trial, and once again, we are very sorry for the spam.”

Now Paul Allen, who is the founder of and a serial entrepreneur, wrote in his Google+ wall that Google+ may reach the 20 million users mark by this weekend. Allen did a summary analysis on the Google+ user-base and said that the social networking stream has been successful in surpassing the 10 million mark.

Allen made use of a combination of surnames and population data from the U.S. Census Bureau and made a rough estimate about the number of users in Google+. He later split the U.S. users from the non-U.S. users by using a sample of 100-200 surnames.

“My surname-based analysis shows that the number of Google+ users worldwide reached 7.3 million yesterday (July 10) – up from 1.7 million users on July 4th,” Allen wrote in his Google+ wall. ”That is a 350% increase in six days. The user-base is growing so quickly that it is challenging for me to keep up, since the number of users of any given surname (even the rare ones I am tracking) seems to be climbing every day.”

Allen further predicted that if the same increasing growth rate continues then Google+ will have about 20 million users by the start of the weekend.

Mark Zuckerberg’s Facebook, at the moment in comparison, boasts nearly 750 million active users.