By Neil Versel, contributing editor

October 28, 2008 | SAN FRANCISCO—In a session about online clinician social networks, moderator Enoch Choi remarked that more than half the companies that presented on a similar panel a year ago were no longer in business. And yet the Palo Alto, Calif., urgent care physician and medical project manager at online health community MedHelp.org, remained optimistic that user-generated health care has a bright future.

After all, medical imaging sharing site MyPACS.net, a panelist in Choi’s session at the third semi-annual health 2.0 conference, was purchased by 175-year-old McKesson Corp. earlier this year. A year ago almost to the day, restaurant rating service Zagat Survey began a foray into physician rating, while consumer rating site Angie’s List made a similar move in March.

Perhaps these developments are symbolic of health 2.0 as a whole. There is a lot of promise for user-generated online content to revolutionize health care, yet plenty of doubt about how to make money providing such platforms. And even old-line companies want to participate.

The fact that the top health-IT advocate in the federal government not only made the coast-to-coast trip from Washington to speak at the conference, but stayed for two full days to talk personally with many of the more than 1,000 attendees, added more legitimacy to the sector.

“It’s important to understand that we’re early in the hype cycle,” national health-IT coordinator Robert Kolodner, said Wednesday at the conference. He urged patience for anyone investing in the sector, particularly in these skittish economic times.

“Keep the faith,” Kolodner said. “The fact that [business success] doesn’t happen in the next six months doesn’t mean that it’s not going to happen.”

Kolodner himself had led the development of an interactive portal, the My HealtheVet online personal health record (PHR) and wellness site, when he was chief of medical informatics at the Veterans Health Administration.

Indeed, PHRs are a big part of the health 2.0 universe, significant enough to convince both Microsoft and Google to launch PHR and data-aggregation platforms in the past 13 months. Executives from Microsoft HealthVault and Google Health joined leaders of WebMD, Yahoo! Health, and insurance giant Aetna, owner of PHR firm Active Health Management, in a plenary session on that very topic.

Kolodner, offering commentary at the end of the session, said consumer aggregators were “necessary but not sufficient” to engaging patients and building the nascent National Health Information Network. Google Health product manager Roni Zeiger, used exactly the same words to describe his product, and PHRs in general.

MyPACS.net creator Rex Jakobovits said success in health 2.0 is all about building critical mass. “One that’s there, it’s self-perpetuating,” he said.