ARM is a family of cores. Within each ARM core version there are several implementations with their own the buses/devices that surround the core. Each chip family is a major port.

As mentioned, the core ports that exists - for example the SheevaPlug, Linksys NSLU2, and the old Gumstix (PXA255), make great small stand-alone applications server, routers.

Besides the PDA, smartphones, there is an ARMv7 handhold called the Pandora (http://www.open-pandora.org/) running Linux. IMO, it would take some serious money to support it under FreeBSD.