article in WIRED about the effect of the Internet on the messenger businesshttp://www.wired.com
in the 80's it was the FAX machine...
if you can believe it!
then in the 90's it was the Internet
which over time developed with greater bandwidth and the compression ability and the clarity of documents sent via PDF
as of yet the messenger is the only way to carry an original for a signature or a book from the legal library
but I would guess that in a few years there will be an article about teleporting taking jobs away from messengers on their hover bikes