White powder letters spook Washington as anthrax attack recalled/ Int'l Business Times

Curious timing of anthrax letters arriving at DC schools.  Might they have been sent in support of the child vaccine trial?  From IBT:

Nearly 30 schools in Washington DC have received envelopes containing a mysterious white powder and with ‘AL AQEDA- FBI ’ written on them, the Federal Bureau of Investigation said on Thursday. Preliminary testing has proved that the powder was not harmful, the FBI has said.