WHO site

Information on this page tracks the evolving situation and provides access to both technical guidelines and information useful for the general public : 

http://www.who.int/csr/disease/swineflu/en/index.html

CDC site

http://www.cdc.gov/swineflu/?s_cid=swineFlu_outbreak_internal_001

Guidance for Clinicians & Public Health Professionals :
http://www.cdc.gov/swineflu/guidance

Scientific American Magazine

A Guide to Swine Flu :
http://www.sciam.com/report.cfm?id=swine-flu-outbreak

Swine Flu Questions  (U.S. Department of Health & Human Services)

http://pandemicflu.gov/faq/swineflu/

H1N1 Influenza Center (NEJM)
http://h1n1.nejm.org/?emp=marcom

Pandemic flu site from the BMJ Group
http://pandemicflu.bmj.com