After some discussions at Ted Eytan's blog I've had to modify my previous definition of Health 2.0. Mine lacked an explicit characterization of Health 2.0 as involving the patents' participation. It also lacked the modification of the health care system as one of the goals. I didn't agree with Ted's because his definition does not acknowledge the quality of the information being shared (individual vs summarized) nor does it recognize stakeholders other than the patient.
Here's my a definition:
"Health 2.0 is participatory healthcare characterized by the ability to rapidly share, classify and summarize individual health information with the goals of improving health care systems, experiences and outcomes via integration of patients and stakeholders."
It's no longer my own though as I've taken a good junk of Ted's. Somehow making a definition for Health 2.0 through the blogosphere seems appropriate.