Facebook could hardly be included as part of any current tech bubble. The early 2000s tech bubble included companies spending millions in investor cash on stupid ideas that would never pan out (online pet food, hundreds of dating websites) and having a grandiose IPO before earning even a dime of revenue. It wasn't over-valuation, it was shocking that some of these companies had value at all.

I personally feel Facebook is over-valued but they have revenue and profit. I think it's a bad early investment and will settle way down south of the debut, but they will be around a very long time. They aren't Pets.com.