I have not really studied this issue in depth, but from what I can tell most of the increasing investment activity that they are referring to is occuring in the private investment world - not on stock markets.

With that said, it seems that it would be difficult to call this activity a "bubble". "Bubble" in the popular nomenclature are typically used to refer to developments that can have widespread consequences when they "pop" (Re: the housing bubble, the credit derivative swap bubble, etc, etc).

There has been a lot of private investment activity in the tech world recently, but I think that it would be fear mongering to refer to this activity as a bubble. The Internet in general (and the web specifically) is still a relatively recent development. It makes sense that you will see a lot of investment activity in this area.

This same type of thing tends to happen whenever a major technological advancement spurns rapid innovation (Re: the gilded age). It is merely capitalism at work - not necessarily a bubble.