Following the work that has been done to revisit and polish the Office Blue skin of Substance look-and-feel closer to the original visuals, the last two weeks have seen major improvements in the Office Silver skin that bring it closer to the Office 2007 visuals as well.
Here is a screenshot of the old Office Silver skin:
While the overall direction is right (grays + a combination of yellow / orange colors for active states), it quite far from the original visuals.
Here is how it looks in the latest 5.1dev drop of Substance (code-named Panama):
To see the new Office Silver skin in action on the Flamingo ribbon component, run the following WebStart demo and switch to Office Silver in the Look & Feel task:
If you want to test new visuals and APIs, you will need to take the latest 5.1dev drop of Substance (code-named Panama). Release candidate for Substance is scheduled for January 26 and the final release is scheduled for February 9.