For a very nice overview of Healthcare 2.0 technology and its impact on physician/patient dynamics check this out:
Randeree E. Exploring technology impacts of Healthcare 2.0 initiatives. Telemedicine & E-Health. 2009 Apr;15(3):255-60. Review. PubMed PMID: 19382863. Link: http://www.liebertonline.com/doi/abs/10.1089/tmj.2008.0093
The author does a particularly good job of laying out how Web 2.0 affects information retention, consumer health literacy, and communication trends. Note: this is from a licensed e-journal. Full text of the article is available online for users of the UCSD network (or other subscribing institutions).