Wired mag has a good look at the technology that will make the new superscraper that will stand on the original spot of the Twin Towers.  Starting with a fortified steel and 3ft concrete core; the design's steel frame will interconnect to distribute load in the event of another terrorist attach or cataclysmic event.

The tower has a 200-foot-tall, bomb-resistant concrete base surrounded by a multi-layered glass-curtain wall designed to be impervious to any kind of explosion.

The scrapers are supposed to be done by 2011.  I've been avoiding Ground Zero for five years- the dense smell and light smoke that permeated the city when I was there one month later has never left me.  Once the memorial is open, I'll go there.