Just to tag along - I was surprised when I first saw early 1920s typographic/graphic design (esp. book covers) just how closely the newer "flat" UIs resemble that period's style.

EDIT: As an example, here's a 1925 German journal cover that would look only slightly out of place in Windows 8: http://typographyhistory.tumblr.com/post/871290549/typograph...