Can Facebook – a company that turns an estimated $2 billion in annual revenue – have a market value 25 times as high?

Goldman Sachs and a wealthy Russian investor apparently think so. The pair invested $500 million in the social media giant, with a view that the actual worth of the company is $50 billion.

“For Goldman, this is a great strategic play because not only do they have the possibility to be at the front of the line when Facebook eventually IPOs – which many believe to be in 2012 – but they also have this great branding of having these assets and attracting new investors,” Evelyn Rusli, one of the New York Times reporters who broke the story, told CNN.

The report adds to the fear that a Dotcom Bubble 2.0 is forming, an idea that gained ground when Google recently offered to buy online coupon company Groupon for $6 billion – and was turned down.

Rusli said of Facebook: “Even though their revenues are relatively low, compared to their huge valuations … you’re buying into the future of the web.” With an estimated 600 million members worldwide, many think Facebook will increasingly influence – and, at some point, become a player – in how goods and services are bought and sold online.

Yet there remains a waft in the air of 1999, when dotcom companies were being valued by what they are expecting to produce, not what they are producing now.

So where does Facebook now rank? Based on its valuation, it is larger than Yahoo and Ebay, but below (at $82.7 billion) and nearly one-third the size of Coca-Cola ($151 billion). At Monday’s close, Google was worth $193 billion.

Social media journalist Shira Lazar noted the company was valued in June at $25 billion “so that’s a huge jump,” yet in December Facebook had more traffic than Google in the U.S. for the first time. “This is the beginning of their growth … they haven’t even tapped into China yet, which has one-third of the world’s internet users,” Lazar told CNN.

Speculation is rife that may soon change, since Facebook founder Mark Zuckerberg was seen traveling in China last month.

Still, is Facebook really worth $50 billion? Or is this the foamy top of a new dotcom bubble in the making?