The details are in USA Today.
Basically they are renumbering the comics (to create all new #1s), and are trying to make their classic characters like Superman and Batman more relevant for the 21st century.
How will they be more relevant? Here's what the writer says: "What's the human aspect behind all these costumes? That's what I wanted to explore."
Sounds like he's got the finger on the pulse of today's youth. Less action. More character study.