If you happened to tune in to the keynote (
or want to watch it again here), you may have noticed something when Ballmer and crew were showing off Windows Surface. While it is not a major overhaul to the Metro interface, you can clearly see below that the icons that link to desktop apps are now much larger.
Take a look at the bottom image, which was from last night's keynote, and compare it to the top image, which is from and earlier build of Windows 8 and you can see the noticeably smaller icons. While not a major shift in strategy or a new feature, it does show the subtle differences between previous and current builds of Windows 8.