The Arch Linux is not always Linux it can have other kernels, like for example the PacBSD which is the Arch with the kernel of FreeBSD . The Arch Hurd are the Arch packages with the kernel GNU/Hurd and logical with the GNU tools. The Arch Hurd project was founded on an Arch Linux forum thread in January 2010, and after a few weeks of much input, it has progressed to the point where it can boot into a virtual machine.

Source: LXer – Meet the Arch Hurd