A new hot online Web site/social movement is costing companies billions in lost productivity. Haven't we heard this tune before?Fill in the blank:

___________________ costs businesses billions of dollars annually.

A. Amazon.com B. Google C. Napster D. iTunes E. All of the above

According to a recent study by security company SurfControl, Facebook, the online social networking site, is costing companies in Australia $5 billion a year in lost worker productivity. And though it's Australia where SurfControl did the research, that lost productivity is easily extrapolatable to other countries, including the United States, where Facebook is growing in popularity by leaps and bounds.

SurfControl arrived at its somewhat arresting figure by simple -- and simplistic -- math: "If one employee spends one hour of company time on Facebook every day, it potentially costs his or her employer more than $6,200 per year. Factored across the 800,000 businesses in Australia, that one wasted hour a day adds up to a productivity loss of $5 billion annually for the Australian economy."

But doesn't this all sound awfully familiar? I seem to remember the same criticism being leveled against just about every online business model/social phenomenon to come down the pike, from Amazon.com to Zillow.com. Every year some research firm publishes eye-popping dollar figures for the productivity lost due to workers checking scores online during the NCAA Men's Basketball Tournament, a.k.a. March Madness. Yet, I don't seem to remember American business grinding to a halt during the month of March.

And correct me if I'm wrong, but wasn't the same criticism brought against e-mail back in the day -- that workers would waste time e-mailing with colleagues and friends inside and outside the organization? Now, that notion seems almost quaint: Who has time to e-mail friends -- and who wants more e-mail in their in-boxes anyway?

If companies don't want their employees accessing Facebook at work, they can simply block access to it over the corporate network. Do you block access to Web sites at work? If so, which ones?

But don't be too hasty. For one thing, the threat to worker productivity that Facebook represents may turn out to be overblown, like that of Amazon. Also, Facebook is a legitimate social phenomenon, along the lines of Napster and YouTube, and may well represent a new way to conduct business -- at least to communicate and collaborate.

Before the implications are completely understood, let's not shoot ourselves in the, um, face.