While there may be some unsustainable speculative behavior going on, I doubt any startup with reputable VCs on the board would do anything close to what Madoff did. Even the dot com crash was mostly about bubbly ad revenue and selling to the bigger fool, not massive fraud.
That suggests startup land is filled with a few fake gold rushes, and in any gold rush, those who deal in oxen and wagons tend to do well. Maybe the oxen dealer here is Google Adwords, StumbleUpon, and anyone else that allows you to buy your traffic to temporarily juice Alexa / Compete results (I've heard enough anecdotes to know plenty of people advocate this tactic).
I wonder which startup will turn out to be the big Madoff Startup?