For those of you with a number of different Google accounts — say for work, personal, your domain name, etc. — Google is rolling out an update to its multiple sign-in system. The switch accounts button is gone, replaced by a list of all of the logins you're currently signed in with, and an "Add account" button below lets you sign in to more accounts. Hit the button and you'll be directed away to the sign in page of the service you're on, but once you've logged in each of your accounts is listed below and are more easily accessible.
It's a minor change over the older system, but one which means users will need one less click to get to their accounts. It's also far more intuitive, making it more obvious to users which of their accounts they've signed in with. Multiple accounts are still only supported by some of Google's services — elsewhere (e.g. Blogspot) you'll be automatically signed into the first account you logged in with.