I cant find an option to turn off the Computer, but i think that would be a great Function.
I'm using my PS3 in the livingroom and my computer is in my office, so i've to go to my office anytime I wanna switch off my computer.
Normally I'm working till evening and turn on the PMS to stream a movie to my tv at the livingroom.
After that I don't want to go to the office anymore.
I wonder that there wasn't any option to display e.g. an entry in my PS3 at the PMS selection that should be named like "Turn off PMS and Computer".
So I decided to try it here.
Eventually I'm blind and this feature is already implemented but I did not find this option.
If not I'm suggesting it here right now.
I guess this isn't attended with much effort?!?!?
Maybe I'm wrong, then it will take some time, but i truthfully hope u can add such feature in the near future...
Hope you guys understand what I wanna tell you
as already mentioned my english is really bad.. 
Greetings
Chris