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.