Setting a Static Ip for the Riocar is great!
It comes in handy for having a bookmark to Hijack's Web and Ftp Services.
It allows for developing things radpily without worrying about the IP everytime you reboot.

There is one thing to note however. If you have it set to a static IP at home, and you connect the Riocar to another computer (at home or at work), you might need to use a USB cable to be able to re-configure the player to use DHCP to be able to connect to the player again.

It's better to let DHCP assign the same IP to the player than to hardcode it into the player. You might be worth a FAQ entry if it's not already there.