I notice the font-family in the CSS for much of WordPress.com is "Lucida Grande", "Lucida Sans Unicode", Verdana, Arial, sans-serif. For the newly-designed dashboard, the equivalent is "Lucida Grande", Verdana, Arial, "Bitstream Vera Sans", sans-serif. Please can you sort of merge these?
It looks fine on a Mac, Lucida Grande all the way. But for me and other Windowsers, it is Lucida Sans Unicode sometimes, and the more out-of-place Verdana elsewhere (on WordPress.org too).
It would be groovy if you stuck to two master font stacks - a serif one and a sans-serif one.