We wrote an article a couple weeks back that showed Google testing Multiple Account login, well its here today. You can access the mutiple account login area by logging into Google Accounts and then selecting “Multiple Sign in”, then you will be able to choose to use multiple accounts in the same browser. The only apps on Google that support multiple sign in at this time are: Calendar, Code, Reader, Sites, and Gmail. Go ahead and check it out and let us know what you think.
Source: Google Blog