I kind of liked that, it reminded me of the Discworld where light is slowed down by the magical field so that it's as slow as the speed of sound.
The new lighting system means that sunlight will be handled completely differently from torchlight and the other light-emitting blocks, which is presumably what is being done to fix that slow chunk update problem at sunrise and sunset. Also, moonlight will have a blue tint to it while torches will have a yellow tint to them.
It doesn't look likely to be included in 1.7, possibly because Notch has new plans for light when it comes to mob spawning and other adventure things now reserved for 1.8. But it does look like
some other non-adventure things that Jeb was working on will be included, such as shears, stackable fences (yay!) and a few other things.