1. facebook is not something new. When Zuckerberg started developing facebook, LinkedIn was already there. I have one linkedin account, 2 facebook accounts. In linkedIn account i have more than 300 friends (gosh! one day i even found Obama and Hilary just one link away), in facebook i have about 100 friends, but guess how much time i spent on them: no more than 2 hours a month in linkedin, no more than 2 hours a year in facebook.
2. facebook is a new toy of younger generation, the younger generation likes it of course. But they are easy to get bored. Unless facebook uses its cash to transform their business, otherwise god knows. I recall 12 years ago a company called broadcasting.com was hailed for its new concept and did reap tons of cash ( i was about to work there before the acquisition) but who knows where is it now.
3. many companies use facebook to advertise their products but block the access to facebook in their intranet. Why? businesspeople are shrewed.