The caves in Keep on the Shadowfell may well be the first time players come to grips with the new illumination rules. Where previously the crypts had been lit by goblin torches, in the caves the players will have only as much light as they bring with them.
This brings into focus a design disparity in the 4th Edition rules. Elsewhere, we've seen how the sundry items of exploring and travelling crap have been folded into a neat "adventurer's kit". The encumbrance rules are forgiving, allowing even the weakest of characters to lug around plate armour, two polearms and a backpack full of loot without penalty. These are good design choices; we don't need to analyse how our heroes make camp or stay fed any more than we need to know how often they use the toilet. The focus stays firmly on what D&D does well, and away from the minutiae of daily living.
Lighting is problematic, though. How far you can see has very real effects on your decision making, your tactical situation, and on the mood and atmosphere of the game. It seems like something that there are benefits in paying attention to. On the other hand, it's a bitch to track. Putting aside virtual tabletop technology, there is simply no easy way of marking the boundaries of multiple moving light sources.
4th Edition can't decide which side of that problem it wants to fall on. It provides a little over half a page of rules for lighting at page 262 of the Player's Handbook. It also sets out the usual illumination equipment. A torch lights 5 squares, a lantern lights 10, and these are both items that involve a naked flame so someone has to forfeit their shield or weapon in order to carry them.
But then it mentions "sunrods", which magically illuminate 20 squares in every direction and can be safely strapped to the haft of your polearm or suchlike. They cost two gold pieces each, burn for four hours, and you get two of them packed right into your adventurer's kit. They render every other form of illumination in 4th Edition completely redundant; there's no good reason that you can't have one of these tied to every player's helmet all the time.
I suspect the intention was to provide sunrods for groups who just can't be bothered tracking lighting, and DMs who like doing it old-school can house-rule them out of existence. That's a pretty good solution to the problem, but it would be nice if this intention was stated. Would it have cost so much to have a little sidebar talking about sunrods, illumination, and play preferences?