I'm currently in the process of writing an sms daemon process that will send and receive text messages using a mobile phone or modem using dbus.
It uses libgammu to communicate with the mobile device, and it only works with the current dev snapshots of libgammu (I found a bug that was subsequently fixed upstream by the maintainer).
it's checked into the linuxice svn repo here:
I'll include this with LinuxICE2 if it is useful to anyone.
NOTE: yes there are 2 other sms daemons available for Linux. I didn't like how either of them worked using files or mysql to send/receive. Mine is much more simpler and doesn't require you to have a database or create some special file somewhere. Mine is also c++ (while the others are in c).