There are already plenty of conspiracy rumors about what is in the center of the new courtyard. My favorite one says the Tomb of Steve Jobs is at the center of it with some of the deep foundation work spec'ed out in the plans at the center of the courtyard.
The reality is that they are planning on a time capsule at the center of the courtyard containing first versions of major Apple products such as the Apple I, Apple ][, Lisa, Mac, iPod and iPhone. If all goes as scheduled, the new campus is in full operation come the summer of 2016 on Apple's 40th anniversary. All these products, and probably a NeXT box too, are placed in the time capsule for opening after the next forty years of Apple the summer of 2056. Intel did this with their new building in Santa Clara back in the 90s.
I'm glad the proposal for a "Tree of Life" in the center of the courtyard a la Avatar got shot down. Trees are great, but not worth worshiping nor hugging.