During the lift-off of the Discovery shuttle, a large piece of foam broke from the shuttle's external tank - this was a bit of a surprise, given the years of work devoted exactly to avoid this shedding in the wake of the Columbia disaster.  As a result, NASA decided to indefinitely suspend further flights until further notice.  A similar foam break damaged the wing of Columbia during its launch, and subsequently caused that shuttle's disintegration during its reentry into the atmosphere in 2003.  Despite that, the Discovery is OK, and there was no observable damage caused this time around, and NASA hopes shuttle flights will be resumed quickly.