MSVC 2005: _CPPLIB_VER == 405
MSVC 2008: _CPPLIB_VER == 503
MSVC 2008 SP1: _CPPLIB_VER == 505
MSVC 2010: _CPPLIB_VER == 420
MSVC 2012: _CPPLIB_VER == 540

References:
http://www.digitalmars.com/d/archives/c++/stlsoft/Request_for_help_from_VC_users_-_it_ll_take_you_2_minutes_-_1978.html
http://social.msdn.microsoft.com/Forums/vstudio/en-US/441d7dce-b9e7-4831-9a9d-8f67bab30865/vc-2008-thiscall-and-cdecl-regarded-as-identical
Local MSVC installs