The rocks are throwing back to futuristic sci-fi... wait? Can you throw back to the Future?
It does beg the question of what are they trying to do. Somebody is a big fan of 60s sci-fi at Disney. Personally I much prefer the Steam Punk'd version of Disneyland.
This is something they can do to refresh Tomorrowland without closing anything or doing construction. IMO Tomorrowland needs a drastic makeover (I would love a steampunk version as well!), but there's no way they can do that anytime soon. In the meantime I give them credit for doing -something- to refresh the area and enhance what is already there. I reserve judgment until they're finished, and suspect they will be pretty cool-looking.