The funny thing with personhood conferral is that it was an obiter dictum (sort of non-binding comment made by the judges that is not part of the official decision) that was interpreted by the court stenographer in the 19th century Santa Clara County v. Southern Pacific Railroad (whose case was ruled in favor of Southern Pacific on a technicality rather than any explicit ruling on the personhood of corporations).  So now with Thursday's Citizens United ruling, it will be interesting to see whether corporations will have to be federally chartered and thereby be revoked of constitutionally protected status or whether this case opens the door to potentially unfettered powers granted to corporations, now that campaign finance is protected "free" speech under the 1st Amendment.