Google Chrome OS to Feature Single Sign-In, Ban Other Browsers?

In a line of code in Google's Chromium, a reference was found to a "login manager," which is being taken to mean a single sign-in for all programs on the OS. But what does that mean for non-Google software?

This is all total speculation, but a writer on ReadWriteWeb suggests that it may mean Google intends to lock down Chrome OS to only use Google software, in order to keep things simpler and easier. After all, it's tough to use a single sign-in (SSO) cookie if you don't control the software being signed in to. However, I don't think this is likely—all of Google's software (Gmail, Picasa, Chrome, Blogspot, Earth, etc etc etc) uses a single sign-in, and I think that's all the phrase "login manager" implies. But the question remains: In a browser-based OS, what happens if you want to change browsers? We'll have to wait for more information before we know. [ReadWriteWeb via Electronista]