Effect Measure has a nice post on the origin of genes in the present H1N1 strain making the rounds, and it adds some subtlety to the story I relayed a couple of days ago.
In short, the genome appears to be composed of pieces that have all be circulating in pigs for many years, yet some of those genes may have originally come from human and avian viruses.
I took a few minutes last night to add tags to most of my old posts about SARS, H5N1, vaccines, influenza, and infectious disease. I also fixed a few links still broken from the ISP switch last year, including the SARS outbreak timeline in "Nature is Full of Surprises, and We Are Totally Unprepared".
Update: Here is another good 2009 H1N1 Flu Outbreak map from Google.