Dave Massy has amassed some information about the new WinHEC Longhorn build (4074) and it's available on the Longhorn Developer Center in the "Conference In A Box." The idea is to bundle the set of conference-related materials together into a kind of "virtual event" so that even folks that didn't get to go to WinHEC can get the Longhorn information that was provided there. The plan is to gather this same kind of material for future Longhorn community technology preview drops.
