Declan Butler has updated his avian flu map and made some changes. First he’s changed the KML to a network link so you don’t have to download any new files to see the weekly updates, second he’s refined the datasets to help better understand the outbreak (Human cases, Outbreaks in poultry, Gridded poultry density of the world, Bird breeding and overwintering distributions) and third he’s gone ahead and is now using ESRI ArcGIS with Arc2Earth to generate the Google Earth KML. What a great example of using ArcGIS for analysis and Google Earth for distribution.
Update - Brian Flood has a great writeup on how simple it is to use Arc2Earth to make very professional Google Earth presentations of your GIS analysis. It is also a great look at how complete Arc2Earth is with its Google Earth integration.