Judging by the opening day of the hugely popular Web 2.0 Expo in San Francisco, the bubble – or at least some of the hype that led up to it -- is back.

It wasn’t just the massive crowds or the blatant self-promotion of speakers like Amazon.com Inc. CEO Jeff Bezos who used his keynote solely to pitch his company's products. But in at least one instance, the response – or lack thereof – offered by the Web 2.0 crowd spoke volumes.

Tim O’Reilly, CEO of O’Reilly Media, which sponsors the much-hyped confab, kicked things off on Monday by revisiting all the doomsaying that preceded the burst of the Internet bubble a few years back.

“A lot of people now say it’s turning into another bubble,” O’Reilly said, in a remark clearly intended to allude to the opinions of uninformed people not actively involved in Web 2.0 projects.

Yet when he asked audience if they believed Bubble 2.0 loomed, one could almost hear crickets chirping, with audience members shifting uncomfortably in their seats.

A later panel examining whether startups today were being built to last or built to flip featured some entrepreneurs who had managed to keep buyers at bay and operate their companies independently. But even they conceded there remained a lot of pressure, from everyone from employees to their own family members, to sell.—Andrea Orr

See additional Web 2.0 Expo coverage at VC Ratings