I remember visiting a dojo one time on my travels because I wanted to practice. The technique was a shomenuchi-kokyunage. I attacked my woman partner and as my slow, cautious shomenuchi came down she turned off to the side, turning, and pointed to the mat in front of me. I stood there confused. She became angry (as so many "spiritual" people are wont to do when the world doesn't do what they'd like to make it do) that I wasn't conforming and rolling myself away. I like to think that she had a bit more of the "internal power" that some of the posters are talking about in this thread. But that's not the traditional sense of what it means.
Perhaps people should define how the "internal power", the "ki" they're talking about works in an actual technique of Ueshiba's Aikido, so that we can get a baseline definition going of what "internal power" is?