There is no "Google version". Internally, we use the same SSH app that you would use, which works great. It's not a terminal: you can't do anything locally. But it's a perfectly decent developer environment as long as all you tools and editor are terminal or web applications (mine are).
They have been working on Secure Shell for a while. You reminded me and I just fired it up and it looks like there have been some improvements since it was first released.
You can download the ChromiumOS source code, build it, and install it on any available piece of hardware. (Though the hardware can't be too lightweight; I tried this on an Atom-based eeepc and it's just too slow. A virtual machine on a modern desktop works fine, though, if you just want to see what ChromeOS is like.)
You can also install your own build on an actual Chromebook, of course, but you lose automatic updates and the secure boot.
You might also consider porting the features you desire to a NaCl app, or contributing to NaCl to add things you need. (Emacs is on my todo list, though not in the near future.)