http://docs.fedoraproject.org/install-guide/f9/en_US/sn-expert-download.html says:

   "Download the boot.iso image for a minimal boot CD or USB flash drive.
   Write the image to the approriate physical media to create bootable media."

I read this as "boot.iso contains everything needed for a minimal install".
In actual fact, it's saying that boot.iso is a minimally sized image for
fast downloads, but still needs an external source of packages. This is
reinforced by the next paragraph, which says that netinst.iso is a reduced
size boot CD, implying that boot.iso isn't, which further lends credence
to my interpretation.

The wording could certainly be improved to make this clearer.