This seems to have quietly appeared on MSDN. I knew it was going to be available soon, but didn't notice it until today when searching for something related.
Integration Services will sometime emit errors with cryptic hex numbers. The full list of errors is now available in one place with the hex numbers and descriptions.
http://msdn2.microsoft.com/en-us/library/ms345164.aspx
Enjoy,
Universe.Earth.Software.Microsoft.SQLServer.IS.KirkHaselden