From Cygnus Solutions:
Cygwin (64-bit) is a collection of tools which provide a Linux look and feel environment for Windows. Cygwin is a DLL (cygwin1.dll) which acts as a Linux API layer providing substantial Linux API functionality. The Cygwin DLL currently works with all recent, commercially released x86 32 bit and 64 bit versions of Windows.
What's new in this version:
Version 1.7.24 allows application override of posix_memalign.