According to Microsoft on April 1st from 0200-0500 PT Xbox Live will be offline for maintenance. As a result, also the ‘My Xbox’ section of Xbox.com will be unavailable, and the Xbox forums will be in read only mode (you won’t be able to post.) The remainder of Xbox.com will be available.
Find out what time the Xbox Live maintenance will begin in your time zone. And no, this is not an April Fools joke, which I’ll probably have to say a lot today.