The default network config is DHCP for the new installation. I guess you didn't touch /etc/rc.conf in order to setup for a static address before rebooting. And I guess you also don't have setup a DHCP server in your sub-network.
If this is the case, it means that your new Arch ARM box just doesn't have an IP address assigned.
2 Options there:
1. Setup a DHCP server in your sub-network (most of the routers have that functionality)
or
2. Plug your flash-disk (or external HD, whatever) into a PC, mount your root partition (providing you can mount it, meaning that you have a Linux box, or whatever other option you have for ext2/ext3/ext4 partitions), then modify the file
<your_mount_point_here>/etc/rc.conf to setup for a static IP network. Some info here
https://wiki.archlinux.org/index.php/Rc.conf#NetworkingThen properly umount your disk, plug-in into your (unplugged) Pogo and go for a plug. Into a few seconds you should have it into your network.
If it doesn't work, you have re-do the mount of your partition (either "/" or "/var" depending on your fstab), and verify
<your_mount_point_here>/var/log - check the
daemon.log,
messages.log or whatever you like. At this point you're just interested if there was any activity at all (did it boot, or not), then troubleshoot.