Visual Studio Update 3 adds some new warnings for precompiled header generation. One of these, C4598, will prevent precompiled header builds of framework code due to our warnings as errors policy.
A fix for this issue is to add the new warning to the list of disabled warnings in the project file. The easiest way to do this is to do a search and replace across your source tree for *.vcxproj files and replace "4627;4654;" with "4627;4654;4598;".
I need to work out what the implications of this compiler change are on how our precompiled headers are generated.