Google has always struggled with adding multi-account support to their products, and Chrome OS has caused many users headaches. The rise of Gmail and Google Apps means that many users, like myself, have multiple Google powered email addresses. If you try to manage more than one on Chrome OS it becomes a productivity nightmare, that Google has yet to discuss. There is no quick way to switch between accounts on the operating system. Google is experimenting with new and improved multi-account support that would let users run different accounts in separate windows at the same time.
Google employee and Chrome fan, François Beaufort discovered the experimental code which would enable this feature. If you want to try this out now you can switch to the developer channel, though that build has a lot of bugs still. There is also no guarantee the quick switching feature will make it into the normal build of Chrome OS.