Speculations about the public debut of the company behind the social networking Facebook, which according to many is the most challenging company in the Silicon Valley now, continue, informs Reuters.

The founder and CEO of Facebook, Mark Zuckerberg, until present has remained silent about the IPO plans of the social network, with the exception of an interview in January, which defined the public debut of the company as "least likely".

However, this does not prevent bloggers and investors to interpret any act of the company as a preparation for a potential initial public offering of shares.

Facebook's expansion, which already has 550 employees and the hiring of former employees of Google Inc on executive positions, only reinforces the speculations.

Excitement around Facebook is guaranteed, according to risk investors, given the explosive increase in the number of registered users of the social network. The number of members has increased more than three times to 70 million since April 2007 till now.

Advertisers are attracted by the enormous opportunities offered by social networks, where millions of people often publish their tastes and interests as part of their online accounts. Such behavior allows advertisers to target messages to specific target groups.

Social networks become a favorite place for people, so the so-called Web 2.0 companies that came after the age of dotcom companies are evaluated so expensive.

The software giant Microsoft purchased last year a share of Facebook worth 240 million dollars, which puts a market value of 15 billion dollars of the four social networks.

The founded in January startup company Slide Inc, which enables people to create their own photo albums on the World Wide Web and to publish their accounts for social contacts received financial injection of 50 million dollars, which would have given it a market value of around 500 million dollars.

The popularity of Facebook is so large that, despite the weak IPO market in the moment, the primary public offers of the company would have success, analysts believe.

Overall, however, the market for IPO remains a challenge for most companies this year. Only five companies supported by venture capital have organised IPO-s in the first quarter of the year in the U.S., compared to 18 for the same period last year.