I say that because Todd Howard was lamenting in one of the podcasts how Ladders had always been such a huge challenge for BGS, and in a funny way they had tried and failed in multiple games to get it right - so they weren't added in a realistic way (Fallout3 just uses teleporting to simulate going up/down).
However in the Trailer we see clear evidence (unlike in Oblivion) of a ladder, prominently taking lots of space in the Bar scene where the thief/assassin backstabs the NPC. If you look to the left of the player/NPC, there is a big, well-defined ladder against the wall.
Something tells me that if they didn't get ladders right, we wouldn't be seeing them prominently displayed like that. I could be seeing things (I have Skyrim-colored glasses super-glued to my face), but I'd be willing to bet lunch that we'll see Real ladders this time.