I spent a couple minutes trying to figure out what MSYS2 was from the project page/the project wiki/Google, and then just gave up.
Really, a single sentence on the summary page at http://sourceforge.net/projects/msys2 and the wiki at http://sourceforge.net/p/msys2/wiki/Home/ would go a long way.
For anyone else in the same boat, I assume this is a replacement for MSYS, which according to http://www.mingw.org/wiki/MSYS, is a "collection of GNU utilities such as bash, make, gawk and grep to allow building of applications and programs which depend on traditionally UNIX tools to be present."