I know it's a few years old, but I was Googling around the interwebs and stumbled across this from 2012. Very interesting to read about how the original UO technology was set up.
http://www.quora.com/What-was-the-technology-stack-driving-the-original-Ultima-Online-servers
...la
http://www.quora.com/What-was-the-technology-stack-driving-the-original-Ultima-Online-servers
...la