I know there's a breakdown of Sonic the Hedgehog physics found here, and I was wondering, does there exist a breakdown of any of the Mario games? Something similar to this but for Mario is what I'm interested in!
found a detailed breakdown of Mario Physics:
I don't know about a breakdown of the physics, but there are commented disassemblies floating around the internet. Romhacking.net, nesdev.parodius.com, Acmlm Board2, SMWCentral and their respective forums would probably be the best places to get that kind of information. The document sections of those sites have enough information to compile your own guide.
Well, I know this question is kind of old but since I found this site was higher ranked in google than the actual answer I thought I'd post a link to this description of the basic falling physics of multiple Mario games
Gamasutra did a feature on the physics of Super Mario Galaxy some years back ... probably not what you're after if you're more interested in the 2d versions. Link here: http://www.gamasutra.com/view/feature/3593/games_demystified_super_mario_.php