It’s nothing (yet) like the 2000 bubble. Back then, Howard Stern and his minions talked for hours on the air about which tech stocks to buy, companies simply made up non-economic metrics (”page visits”, e.g.) to justify an IPO or a stock price, and people were getting second mortgages just to buy tech stocks.
I don’t think we’ll be at the limit until we see a couple of those unmarked Google / Yahoo / Twitter luxury buses tipped over or torched.
This is a story about an example of an idiot company, not a bubble, believe me, I was at ground zero in the last bubble, what is going on now is nowhere near that. What mostly is going on is the fact a decade has been nearly lost between the last bubble bursting and the financial crisis, so you are seeing 10-15 years of undergrowth, start to come back hard.