What a great post. I am not familiar with the 1994 US Supreme Court ruling. I would love to hear Rob Tiller's take on this comment (which might as well be an article posted in its own right).
I'd be more surprised if people said DRM had *never* prevented them from doing something they wanted.
My sister had all her music in iTunes on a Mac. This was before they started selling non-DRM music. She wanted to move that music from one system to another but had already exhausted the number of machines that could be authenticated to her iTunes account. I forget the details, but she ended up burning it all to mp3 CDs and reimporting it. This is transcoding and reduces the quality, and also is obviously a pain in the butt.