As I mentioned in my recent Globe and Mail column on the Facebook IPO rumours, I don’t think there has been so much frenzy around a tech startup and its valuation since the Google days, although the debate over YouTube’s value (thanks in large part to the always game Mark Cuban) runs a close second. We now have valuations that run anywhere from a mind-boggling $10-billion — and this is for a company with annual revenue of about $100-million, at last estimate — all the way to zero. The big debate lately has been whether Facebook’s poor performance on the advertising front makes it worth less (or worthless), or whether it just means that advertising isn’t the route to profit for a social network, as my friend Scott Karp of Publishing 2.0 describes here. I, for one, hope that Facebook does do an IPO so that we can let the market decide what the company is worth. Sergey Brin says he’d be happy to talk to Facebook but isn’t planning to buy it, and thinks it is building a great company on its own.