Whats mob seige?
Mob siege is where a ton of mobs, usually only one kind (like a zombie siege, but there can be multiple mobs there) assault a city and try to kill all of it's occupants. Jeb is working on adding in a Zombie siege function to minecraft in the next update, so that should be cool.
Dinnerbone is. Dinnerbone did most of the 1.3.1 stuff yet all the credit goes to jeb_ like right here.
Again, why the hell does it matter? I don't understand people's obsessions with crediting each individual person that works on any given project. When you compliment some new update World of Warcraft does, do you say "Thanks to Jim and Stacy down in the graphics department, that new orc skin looks really good. And Terry did a good job on that item drop from the newest raid boss we fought recently. And Tracy, god, she does such a good job on sound."
No, you dumbass, you compliment the group as a whole with a name, which in this case happens to be Notch or Jeb. No, they may not have done the ACTUAL work, but they started everything and led the damn department, so it might as well have been them because it couldn't have been done without their foundation. No need to be a prick about credit.