One thing I am interested in with the eventual switch to SmartThings from my existing Homeseer system, is the support of serial devices. I have the following I am now using as part of my current Home Automation System:
DSC Alarm control via the IT-100 module. http://www.dsc.com/index.php?n=products&o=view&id=22
This allows complete control as well as status reporting to my home automation system from my alarm. Due to this, I dont even have alarm monitoring. I do it myself. I can Arm, Disarm, see status of Zones, etc all using this module. They do make an IP equipped ethernet version of this module, but the IT-100 is serial and much cheaper.
I use this interface to create my own events, for things such as intrusion (send tweets and SMS, control Z-wave Siren http://www.fortrezz.com/siren.html)