CMake is a cross-platform and open source build system for Visual Studio, GCC, ICC, Watcom, Borland, CodeBlock, XCode, Eclipse, 32 bits / 64 bits, etc... It allows managing a project independently of the development platform. CMake became one of my favorite tool the past year!
From the RC2 changelog, I mainly 2 great adds. First, CMake 2.8 provides Visual Studio 2010 support. Second, a new command "cmake --build" allows to build any solution that CMake has generated. For example, no need to launch Visual Studio to build a Visual Studio solution!