I can understand that some people enjoy pair programming, and there are some situations like knowledge transfer where it may be appropriate. But I'm not sure it would fit with the way I solve problems. I don't know what I'm doing half the time -- I have to experiment and hit my head against the wall and continually inspect APIs in an IPython repl. I go back and forth between a console and a browser and emacs a mile a minute.
When I've had to program with another person watching, my productivity screeches to a halt.