The new trick allows you to sign into multiple Gmail accounts at the same time.
Google is rolling out an update to the Manage Account page for all of its users this week, according to the Google Operating System (unofficial) blog. The new account page will let you log in and out of multiple accounts at the same time using a drop down menu at the top-right of the page.
Here’s a screengrab of what we’re looking at:
Once logged in, you’ll toggle between the following Google’s URLs: http://mail.google.com/mail/u/0/, http://mail.google.com/mail/u/1/, etc.
As with a lot of Google products, it is a beta.
I can’t currently use this feature (it hasn’t been enabled for my account yet), but I currently flip back and forth between my Apps Gmail and my personal Gmail account and often get confused where I am sending from. This will only make that more difficult. Hopefully, Google lets you skin each Gmail account differently.