OverTheGeicoE writes "The Wall Street Journal reports that Google+ has added 20 million users in just 3 weeks. According to the article, no other site has recorded such high growth in such a short time period. Twitter did something similar once, but in months, not weeks. It's especially surprising considering that access to Google+ is by invitation only. Why is Google+ growing so quickly?" A recent article at O'Reilly Radar offers a possible answer to this, calling Google+ "the rapidly growing seed of a web-wide social backbone," but one that requires openness from Google to really flourish and supplant Facebook. The growth of Google+ will be helped by their acquisition of Fridge, a startup company focused on group sharing. Meanwhile, recruiters and marketers are already eyeballing the growing social network and licking their chops.