In an interview on CNBC LinkedIn CEO Jeff Weiner tried to address skepticism.

Jeff Weiner, LinkedIn CEO, said, "We have over a hundred million members. We're growing the fastest absolute rate in the company's history - faster than a member per second. To put that into context it took us nearly 500 days to add our first million members, it took us less than seven days to add the last million members and half of that is coming from overseas. So it's truly global growth at this point."

In 2010, 45 percent of LinkedIn's revenues came from online advertisers looking get their message out to those more than 100 million members worldwide. But the biggest source of revenues came from other services.

That's a key factor as LinkedIn looks to differentiate itself from other hot social networking companies expected to come to market like Facebook, Groupon, and Zynga - which make up the new "it" crowd for investors.