Investors hungry for a pure play on social networking will have a new name to chew on this week.

LinkedIn is on track to price its IPO tomorrow night and begin trading publicly come Thursday.

It's going to be a hot deal. Underwriters now expect to price the offering between $42 and $45 a share, $10 above its previous range. In other words, demand is scintillating. It shouldn't surprise anyone to see the stock open above $50 -- if not $60 -- when Mr. Market gets a crack at the freshly minted shares.

Is LinkedIn's valuation making promises that its fundamentals can't keep?

LinkedIn's new range implies a market cap of roughly $4 billion given the roughly 90 million shares that will be outstanding. This may seem like a Web 2.0 bargain compared to what Facebook, Groupon, and Twitter will ultimately fetch on the open market, but it's not cheap.

As the world's largest professional network, LinkedIn connects more than 90 million largely white-collar users around the world. It's a big number, but it's not as if these users are spending as long on the site as they are on the more social network in Facebook.

Revenue more than doubled to $243.1 million last year. Profitability had been elusive until LinkedIn earned a modest $15.4 million last year. Is that worth $4 billion plus whatever pop it nabs in two days?

Users did amass 5.5 billion page views during the final quarter of last year, so there is a healthy degree of engagement even if it's not Facebook's level of stickiness. Whether someone's looking for work, trying to fill a vacancy, or simply has a burning question for peers, LinkedIn is there as the new face of professional networking. Job listings giant Monster Worldwide (NYSE: MWW) and niche hub Dice (NYSE: DHX) certainly aren't growing this quickly. Even the online recruiting arm of China's red-hot 51job (Nasdaq: JOBS) comes off as a relative slacker when pitted against LinkedIn's heady growth.

If LinkedIn is truly revolutionizing the way white-collar job searches and head-hunting is done, one can argue that $4 billion is a bargain compared to the juicy upside. However, if this is just investors hyping up any social network -- the way they have with Latin America's Quepasa (AMEX: QPSA) and China's Renren (NYSE: RENN) -- one has to wonder if LinkedIn will simply be batting practice before Facebook hits the field.

Are you buying or passing on LinkedIn's IPO? Share your thoughts in the comment box below?

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Longtime Fool contributor Rick Munarriz remembers when social networks were an offline endeavor. He does not own shares in any of the companies in this story. He is also a member of the Rule Breakers analytical team, seeking out the next great growth stock early in its defiance. The Fool has a disclosure policy.