Update from New York Daily News:

Police investigate package sent to World Financial Center with what appears to be a grenade

Just some headlines crossing the stream:

NYPD SAYS IT IS INVESTIGATING SUSPICIOUS PACKAGE DOWNTOWN

SOME BUILDINGS AT WORLD FINANCIAL CENTER BEING EVACUATED

And from @NYScanner:

World Financial Center Area being evacuated due to a suspicious package NYPD ESU on scene awaiting Bomb Squad.

More as we see it.