The description of Twenty Twelve mentions the use of an optional display font, I take it it's the custom "Open Sans" font. Since it's "optional", does that mean it can be deactivated? And where/how?
Note that this phrase is not found on the actual page for the theme (http://theme.wordpress.com/themes/twentytwelve/), you find it upon hovering over the theme in question in the Theme Showcase.