I found this blog post about a couple Harvard students who wrote some [GPL'd] software for controlling worms' minds. They can control how these worms move and even make them lay eggs!
The implications of this are obviously huge. This is only an academic project now, but in a couple decades I wonder if we'll see animals used like machines? I guess there's several other ideas you could draw from this, but no matter how you view it, it's a fascinating idea.