I'm still not sure how I feel about the "All the things must be flat" design trend. (Well, that's not true, I certainly hate Windows 8's Xbox-like desktop, the way that the Xbox UI was changed to match it, and the iOS 7 UI update.) Also, I did notice, the other day, how LJ's own user interface was certainly, er, flattenized.
But, I thought this article was interesting:
"[...] companies aren't simply following Microsoft's lead in the quest for flat. There are cultural and technological reasons for this new look and feel."
Also, unrelated (well, related in that the article mentioned that the flat design is reminiscent of these):