The FBI seems to think it's Al Qaeda too, at least according to Trenton Times article (link in post 38).
The known link between the 9/11 hijackers and these anthrax suspects is Mohammad Pervez, a naturalized U.S. citizen of Pakastani origin who shared an apartment in Jersey City with two suspected hijackers.
Pervez also shared an apartment in Trenton with some of the people questioned in these raids; and, he worked in both Trenton and Jersey City, selling newspapers in both train stations.