Why is it that if you download Git 2.0 from the net, you always get a 1.9.4 installer package?

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/.

Git for Windows is msysgit project. The latest version of this project is 1.9.4 so Git is also 1.9.4 in it. This is official Git installer for Windows.

Also there is a note on download page:

The current source code release is version 2.1.3. If you want the newer version, you can build it from the source code.

So you can build Git 2+ on Windows by yourself.