Professional networking site LinkedIn announced today that it just crossed the 50 million user mark. That's not in the same league as social networking giant Facebook, which says it reaches 300 million users, but impressive for a work-focused site, and a formidable challenge for any wannabe LinkedIn-killers.
The Mountain View, Calif. company says its user base has been growing quickly, with the most latest 1 million joining in the last 12 days, compared to the 16 months it took for the first 1 million. LinkedIn has 11 million users in Europe, while India is its fastest-growing country, with nearly 3 million.
Another measurement of LinkedIn's growth -- when new chief executive Jeff Weiner took over in June, LinkedIn reported having 42 million users. So the site has grown 19 percent in the last four months alone.