Actually, IMO, this is the place where Eberron went for kinda lame solution.
Problem: We need transport system in a setting that has high magi-tech.
Solution? They use
trains.
I mean,
trains? They could've been much more creative here - off the top of my head, they could use, say, Phase ships that sail through ethereal plane; and faster Shadow ships that sail through Plane of Shadow (which is more dangerous). They could use telegraph-like* transportation in from of beam of light/cloud of matter (or hey, matter in sate of plasma) moving at high speed/capsules that are bounced along pre-determined path. And my ideas are lame... there are certanly better out there. And they settled on boring trains and airships.
*I mean, original real-life telegraph, that used towers and light signals.
EDIT: Oh, I can't miss oportunity to link OotS:
http://www.giantitp.com/comics/oots0344.html