I agree the multi user aspect is an area that could use improvement. This would imply that you'd be able to have a different set of cookies in each window - something that forces many of us to use multiple browsers or incognito mode to achieve.

One of my biggest gripes about Google's account management, is that you are logged in automatically across all Google properties. I use multiple accounts all the time. Just because I'm logged in to one account on Gmail, doesn't mean I want to use the same account when I visit AdSense, or Google Checkout.

This new capability would at least allow me to work around Google's flawed global account sign-in.