Bubble 2.0

There's been a lot said lately about us replicating the Dot Com bubble all over again and even though a much-respected figure like Paul Graham has stated his believe that we're not in a bubble, the doubts remain.

I'm yet unconvinced by either to be honest; I understand all the reasons why people wouldn't think we're in a bubble, yet I'm very cautious about some of the valuations being thrown around in what may just be a very ambitious funding environment at present.

When all else fails though, fall back on what we know: years and years of data. The above-linked article highlights that (listed) tech companies at present trades on similar ratio's to other non-tech companies, which at least seems to indicate that people outside of the supposed bubble isn't throwing their money at it (which is what I understand happened in Dot Com).

What do you think about the bubble?