He is talking about the old gray status bar. This style of status bar no longer exists in iOS 6, it is now either black or shaded to match the navigation bar. In both situations, the text and icons in the status bar are shown in white or off-white color.
Yeah, pre-iOS 6 the color didn't really imply anything--just when the "colored" version of the status bar was used, then those items showed up in blue, and when the black version was used then they showed up in white.