DRM is especially damaging to education. Yes, there's fair use, but if a DVD is protected, try getting a 3-minute clip for your conference presentation. Soon computers themselves will be hardwired to protect content, just making it harder to use your content legally.
I love my iPod, but one of the things I find frustrating is that you can't transfer music via your iPod from one computer to another. Granted, I circumvented this, but many people I know haven't. It's my music. If I want to have it on my home computer and on my office computer, I should be able to. Here's the relevent clauses in Apple's Terms of Service:
You shall be authorized to use the Products only for personal, noncommercial use.
You shall be authorized to use the Products on five Apple-authorized devices at any time.
You shall be entitled to export, burn or copy Products solely for personal, noncommercial use.
You shall be authorized to burn a playlist up to seven times.
You shall be able to store Products from up to five different Accounts on certain devices, such as an iPod and iPod mini, at a time.
However, they make it difficult to do what you've been authorized to do. I know that much of this comes from pressure from the movie and recording industry.
Some DRM-free stores are popping up--one is mp3tunes.com, which charges only 88 cents/song. Granted, you might not find exactly what you want, but at least the music is yours.
DRM is a good argument for continued P2P sharing of music, however illegal that might be.
You should also see Clancy's post about Lessig's talk at the 4C's.