Google has been rumored to be testing this feature and now it's joyfully here. You can now stay signed in to more than one Google account in a browser window at a time. It's off by default, so if you'd like to get started, hit up google.com/accounts to switch it on. There are quite a few drawbacks though. First, this feature is only supported by six Google products and those are Code, Calendar, Gmail, Reader, Sites and Voice. Docs is coming soon, and I really hope YouTube is on that coming soon list as well.

Second, and most important, Google warns of multiple issues that may come about when using multiple accounts on both the activation page and their help page.

Warning: Enabling multiple sign-in will disable Offline products like Offline Gmail and Offline Calendar, as well as any browser bookmarks you've set to link to your accounts. If you use Offline Gmail, make sure to sync your offline mail before enabling multiple sign-in so you don't lose any messages in your outbox. If you would like to continue using Offline Gmail, Offline Calendar, and browser bookmarks linked to your accounts, do not enable the multiple sign-in option. If you have already enabled multiple sign-in, you may disable it.

That may be an issue for some of you as well. If you can get over these trade-offs, then go ahead and start using multiple Google accounts. When enabled, you'll now notice that your email address at the top right of any Google product that supports multiple accounts becomes a drop down menu for all accounts you are currently signed into.