Past postings have alluded to the astronomical and bubble-like valuations currently enjoyed in the private markets by social media outfits such as Facebook, Twitter, Zynga, Groupon, and others. Now comes word that Facebook’s current financial performance and price/earnings (P/E) ratio may warrant a valuation of close to $100 billion in the private marketplace.

According to an item in today’s Wall Street Journal (wsj.com), the company is on track to exceed $2 billion in earnings before interest, taxes, depreciation and amortization, or Ebitda, in 2011. That is above the numbers from Facebook that circulated several months ago when Goldman Sachs Group Inc. (ticker GS) and Russian investment firm Digital Sky Technologies invested in the closely held Internet company. At the time of those investments, Facebook was rumored to have approximately $1 billion in earnings and the prices paid for those investments essentially assigned a valuation to Facebook of approximately $50 billion. Because Facebook is a private company and not required to release its’ financial performance data, reports of its’ financial metrics are necessarily somewhat murky and speculative.

Those citing this big number cautioned that assessing Facebook’s value is difficult because, besides objective matters such as earnings potential, much depends on market sentiment and the overall economic mood at the time of a public offering. There is scant public information on Facebook’s financials. Given that, some venture capitalists, investors and bankers privately express surprise at what they perceive as astronomical valuations. Since the investment by Goldman Sachs and Digital Sky Technologies of $1.5 billion, valuations of Facebook in the private markets have fluctuated wildly and have recently traded around $70 billion. A spokesman for the Palo Alto, Calif., company said, “We’re not going to participate in IPO-related speculation.”

EMarketer estimates Facebook will have ad revenue this year of $4.05 billion, up from $1.86 billion last year. Wedbush Securities Inc. analyst Lou Kerner said Facebook warrants a bullish view because it is eventually going to take a much larger share of the Internet ad market, while its other lines of business are poised to grow quickly. He pegged Facebook’s profit margin—in earnings before interest, taxes, depreciation and amortization—at about 50%. He said Ebitda should be $1.95 billion this year, and he estimated the company’s value in the public market would be $112.9 billion. Its ad prices, which have long lagged behind major rivals, appear to be rising quickly. In the first quarter, ads on Facebook cost 40% more per click than in the previous three months, according to Efficient Frontier, an online ad performance firm.