We use them as laptop replacements. Everyone has a desktop and we don't allow source code checked out to laptops, so the Chromebook (with ssh) makes a fine developer machine. It's also good for the non-engineers who use things like Google Apps extensively (and this is where it's targeted).
I have a ThinkPad but when it's time for a refresh I will probably use the Chromebook. I don't really like maintaining two machines, and the Chromebook works well enough as a work laptop without requiring me to do anything other than sign in with my Google account.
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).
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.)