I have posted about the need of an OS sometime back in may 2008. you can read it here
some of the words were
NBOS(Next Big OS) will be leaner, faster to boot and visually-may-be-less-captivating but true-to-the-definition-of-OS
Now in NBOS, whenever we login instead of user names, we will be options to login based on the service package we are using, suppose that I am using mail from yahoo, online OPT(Office Productivity Tools) from Google, offline OPT from Microsoft, online web designing package from adobe and WB & offline web designing package from mozilla, so it should give me exactly this environment. NBOS should facilitate single sign-on (SSO) to get into this set of services.
Finally google has recognized the changing needs of the user. Hope Chrome OS is that NBOS