I think this misses the readability of dark color on a lighter background. A dark menu-bar can work on iOS because their are only 4 or 5 items in the menu bar, and each is an icon.

The OSX menu bar uses a mix of text and icons, and I believe is easier to read with dark on light. If it was limited to only a few words like WP7, I don't think it is an issue, but with 4+ text items, scanning dark text on light is easier.