This article in Government Health IT by Brian Robertson is a reasonably good description of the basics behind Health care 2.0. It doesn’t really feature much in the way of actual Health2.0 players other than Revolutions, but it does interview the guy who runs the Health2.0 wiki, Johannes Ernst, who is a leader in the Health2.0 movement (even though he’s more of a general techie than a health care guy).

Oh and I just noticed that Tony Chen has a rather better rundown of Health2.0 companies on his site —Hospital
impact – Consumer’s Guide to the top Healthcare 2.0 websites.