So I went to YouTube, and after watching the Mario Bros. commercial, I found a relevant video: Super Mario Bros. on the 2600. Unfortunately, it's deadly for the eyes, so I won't show it here. Although, it could be possible, just not in the way the video presented (sounds too much like NES and not 2600). You have been warned!
http://www.youtube.com/watch?v=Hc0yGQwvQtA&feature=related
EDIT: Super Mario Bros. is a good game, I just can't imagine how it would've been possible with the 2600's limited capabilities

I've played the hack before. Pretty fun.

The NES was a big improvement over the Atari!

Super Mario Bros. Atari 2600 style. I don't think this game actually exists, and the sound is way better than the atari's capabilities. Cool vid, though.
Wait, nevermind, you knew that.

Actually, the sound was lifted directly from the NES game. Still, I guess I overreacted some. It was just surprising for me, that's all. It's not on the 2600, I know, I was just being, well, worrisome some.

I remember when the guy made that video. He thought that Atari 2600 == low res. (Which isn't strictly true. Vertically, the 2600's resolution and color palette are quite good.) He didn't realize that there were some hard limitations in the 2600's design.

Specifically, it's impossible to have more than 2 sprites visible on the same vertical scanlines. The background is nothing but blocks and only comes in one color.(Two if you count the background.) The background cannot be scrolled smoothly in a horizontal direction, but it can be scrolled vertically.

I won't get into sound generation, which was extremely primitive compared to the NES.

Thus what you see in that video is quite impossible on the 2600. There are much better attempts out there at creating a mario type game, but that ain't it. That's just some photoshopping that the guy thought would work. Sorry.

Now they should do Super Mario Brothers 3 Atari 2600 style

I'm sorry I overreacted. It was just too weird for me, I thought I'd've wanted to share it.

looks like the super mario bros for the graphing calculator only with color!

Yeah, this isn't even remotely what SMB1 would be like on the 2600. It's a quick, unimpressive graphic hack anyone could do in half an hour - do people still actually bother with these? Yawn.

Good lord that was awful!

I've played this hack before.

It simply couldn't be done on the 2600! Even that video can't accurately show how primitive the game would be!