Can someone explain this to me...
 

These are images form the discreet gallery for 3ds max 5. Each image has a caption in the lower left corner. The last image uses something called a "Skylight", which takes forever to render. Is this some technique I'm just not aware of, or might this be a new kind of really cool light?

Looks like a new light in MAX 5. If you read the list above the render time, the middle image has a bunch of omni's (probably in a grid above the object as to similate a light flood from above) the last image has 1- skylight. That looks to me to be a light type.