I didn't realize this at all, but this fact comes from http://www.hiddenmickeys.org/ and apparently it's been confirmed:
"The ball weighs 6 tons and is held up bay a fountain of water. In fact, if it was ever removed the water from the fountain would rise 210 feet in the air!"
Now, I knew the ball weighed a lot and was held up by water, but 210 feet into the air!? Why do they have a big rock there when they could be shooting water 210 feet into the air. Admittedly, they'd need some high fencing around it, but I think that'd be the neatest thing ever. Talk about the scale of Disneyland being thrown off though...how small would the park look when you have a jet of water shooting higher than the Matterhorn!
But seriously, doesn't this cost a fortune in water bills for Disneyland? That kind of pressure would require a ton of water applied constantly. I'd think for such a small "attraction" in Tomorrowland it wouldn't be worth the enormous water bills.