No ladder, just a hatch... There was also ladders on Boarding Party... And plenty on Crow's Nest, along with one on Tsavo Highway. The latest Halo book also says Elites have ladder climbing issues, since they have backwards knees.
I'd like to have some ladders as well. They could double as a walkway if you ended up running out of bridges. I thought of something cool last night as a potential future Forge thing that kind of fits for the ladder conversation. The purple lifts that are on Construct would be a great Forge item. They could only be used in a straight line of some sort(horizontal or vertical), but you could adjust the height/length. So you could use them in place of ladders and since the lifts on Construct spit you out at your desired destination, you don't have to get hung up like I've done a hundred times trying to use a Grav Lift. But I voted for the ladders.
I don't think they actually gave characters climbing animations, meaning this will likely never happen. If you want to create cooler maps, get Far Cry, to bad no one plays it anymore though so you'll have no one to play against.
im not sure, it looks so wierd when you run up a ladder, might take alot of the realism out of the game.
i think it would be greta to have a ladder cause then u dont need to use grav lifts and man cannons to get up to places