There is a new project called "Git For Windows": https://git-for-windows.github.io/
As I explained, it will replace msysgit, with the phasing out of msysgit (Q4 2015) and the new Git For Windows (Q2 2015).
It has a much more recent bash, based on the 64bits msys2
project, an independent rewrite of MSYS, based on modern Cygwin (POSIX compatibility layer) and MinGW-w64, with the aim of better interoperability with native Windows software.
msys2
comes with its own installer too.
The git bash is now (with the new Git For Windows 2.6.x):
GNU bash, version 4.3.42(2)-release (x86_64-pc-msys)
Copyright (C) 2013 Free Software Foundation, Inc.
(as opposed to the old 32-bits msys bash from Git for Windows 1.9.5:
GNU bash, version 3.1.20(4)-release (i686-pc-msys) 2005
).
This 4.3 bash comes with the latest patches.
You can install the SDK in order to build a git 2.x.
(The SDK will bring the right git sources)
Update 2015: you now can test on Windows the latest Git releases (2.6.2+ at the moment): https://github.com/git-for-windows/git/releases/.