Bank one in arizona used to always open at the end of games (it may still, havn't been there in a while). It didn't shake the ground but everybody always stopped whatever they were doing and watched. It is very impressive to see something that big move above you. And even normal noises are a little disquieting so I can imagine any shaking would freak people out really, really fast.

I was at Miller for the first time back in 2001, and they closed and opened the roof after every game while playing the theme to "2001: A Space Odyssey". It was indeed a spectacular sight, and I don't remember it being particularly noisy back then, at all.

But they have had some problems with it -- I've not seen it in operation (and for that matter, open during a game) since '01 and I've been back there for five games total in '03 and '04. However, I've seen other problems they've had. One particularly rainy day I was there, the pivot point leaked, and water was pouring down upon the upper deck seats right behind home plate. My friend (a die-hard Brewers fan) and I were sitting way out in right field, so we got a great view of it. I've heard the same rumor from him, so I would believe that it's not far from the truth.

Now, I'm not THAT kind of engineer, so I couldn't speak for exactly why it might be making the noise, but if I had to guess, there's probably a similar leak in the roof mechanism area somewhere (located directly above the seats I mentioned) and it's caused the gears and such that runs the thing to rust and/or fatigue easier than expected.

And it may turn out to be one of those things that just never gets fixed, sadly.

I've seen the roof open at Enron/Minutemaid. It
made no noise at all.

I live in Seattle... the roof at Safeco makes no/very little noise. It's the trains passing the stadium that can drive you nuts.

I was at Bank One Ballpark during the D'backs first season. They opened the roof at the start of the game. (The stadium is rectangular, so I wouldn't call it a dome.) It opened perfectly smoothly and quietly.

I remember watching a game a year or two ago with the Cards at Miller, and the announcers were talking about how bad the noise was while the roof was opening or closing. That is kind of sad that rather than fix the problem, they'd prefer to just not operate it with fans present.

I went to Miller Park in 2004 to an April Cards/Brewers game. It was drizzling outside, so the roof was closed. However, after the game the rain had stopped and they announced over the loud speaker that there would be a "roof show" (or something like that) starting shortly. The proceeded to play the theme music from "Return of the King" while the ceiling opened. I stayed in the stadium for the entire opening (10 minutes? 15?), then left as they were closing it again. No shaking, and frankly it didn't seem loud, either (although, the music was turned up, so it could have been noisy).

I also caught a game in Toronto back in 1999 and saw the roof close after the game. No major noise there, either.

I'm guessing the Cub fan was passing on an urban legend.