Time to reach 20 million users...

Google+ reaches 20 million users in only three weeks?

"I've never seen anything grow this quickly," said Andrew Lipsman, vice president of industry analysis at comScore. The only other site that has accumulated as many new visitors in a short period of time is Twitter in 2009, he said, "but that happened over several months."

...Of course, Google has a long way to go to reach the scale of Facebook Inc., which has more than 750 million users, and Twitter Inc., which has more than 200 million registered accounts...

...Google+ also has unique technology, such as a "hangouts" feature, that lets people do "video chats" using their computer webcams, speaking to numerous friends simultaneously. The company plans to include Google+ in its suite of online software for businesses...

Google's ability to group users is a decided advantage over Facebook. Whether it has legs, however, is an open question.