I'm trying to figure out what version of the game is the "meatiest" (for lack of better word). Here's what I figure:
Meat Boy (Newgrounds) - The precurser to the main game. Considered a "prototype" by Team Meat rather than a prequel, although the levels are apparently different. This game's levels were remade in future DLC, as far as I can tell, so that would make this pretty much entirely obselete.
Super Meat Boy (Xbox Live) - The "original" release of the game, not counting the flash "prototype". - Exclusive "Teh Internets" chapter where Team Meat distributes level packs. - Longest load times.
Super Meat Boy (Steam) - Exclusive "Super Meat World" hub that's apparently an expanded "Teh Internets" with most of the same content. - Two level editors: a hidden debug one left in the game menu, and an officially supported Steam one. - The most playable characters (some replaced from the Live version). - Has the most active support, although uploading user-made content is supposedly gone.
Super Meat Boy: Ultra Edition (retail) - Comes with disc and unique packaging and stuff. - Super Meat World is available from the start, but apparently there's no level editor feature? - Is overall similar to the Steam release, but slightly downgraded. There are also less playable characters for unknown reasons (licensing?).
Super Meat Boy: The Game (mobile) - No one knows too much about this one yet, but they once again consider it the same game with remade content.
Not counting Mac/Unix ports since I know nothing about them, but I assume they're the same as the Steam for PC one. I'm also not counting Super Tofu Boy...
So from the looks of it, the Steam version is the one to go with. Anything else I should know? And how different are Teh Internets and Super Meat World from each other? That's literally all I know about it. --- Whoever started using the word "canon" in this context, anyway? I hear it all the time now, and I'd like to slap him. - Green Gibbon!