Despite the relative ease of the first several worlds of Super Mario 3D Land I struggled enough in one level to find out how Nintendo helps players who die a bunch. As you'll see in the video demonstration we just shot, the game's designers give you a free, random power-up after two deaths on a new level. After five, you get the most powerful power-up I've ever seen in a Mario game.
The game does not appear to penalize players who use the help system, but that system also appears to only be available the first time you try to go through a level. I've returned to older levels to poke around more and was unable to trigger it.
Nintendo has implemented other help systems in the major fall releases, including a system I used in last year's Donkey Kong Country Returns to have the game beat the final boss for me and the eight-death Super Guide aid in 2009's New Super Mario Bros. Wii.