Amusing list yesterday from the a:c... The talk of a new bubble has now been around for 18 months, since the term Web2.0, with about a thousand possible meanings, got people and the media in a spin.
Although I lack the on-the-ground prespective from the valley, I think it's difficult to call the current state of internet business a bubble. First, you don't have many public companies, so the valuation inflation is mainly happenning on the VC books. That's a much smaller problem, especially given the liquidity levels globally. Second, if you looked, you could see similar exuberance in almost any market (e.g. residential real estate yields in Istanbul seem to hover around 2-3%), so the asset price levels are not isolated to the internet sector. Third, some of the bubblish valuations we've seen (YouTube, DoubleClick, implied Facebook), are truly paradigm shifting companies and not exactly pets.com's.
Not a bubble... Yet..