[hswolff]

It does look like Apple TVs.

It also looks like multi-colored and multi-sized iPhone home buttons.

But that might just be me projecting my own desires. ;)

[chrisdroukas]

Calling it: 1:1 aspect ratio Macbook Square.

[dkasper]

Calling it: Apple will announce its acquisition of Square. (jk)

[hemancuso]

It looks like a bunch of app icon silhouettes

[tjpd]

I think this is the most likely. Apple is steadily pushing the iOS UI elements into the "wider" MacOS platform. This is evident from the last few changes to the Cocoa APIs and the recent requirements for Applications available on the Mac App Store. Desktop applications are increasingly going to be Appified.