Yes, I would be inclined to agree, I do industrial engineering with PLC's and SCADA.
I am looking to use the Arduino platform in smaller self contained installations where the cost of high end PLC equipment is not warranted.
But like terry says,
External connections: protection against voltage spikes and induced currents. What happens if lighting hits the building? Where is real "Ground".
This happened to me today, Tue 6th at 14:30, while I was workinig away programming, check here http://arduino.cc/forum/index.php/topic,130940.0.html
I guess I now have more time to do other things until I either fix or get new Arduino's.
I will be paying moe attention to voltage spikes and some form of ligthning protection now.
First time in 15 years, I guess I am lucky in some way.
Paul