It's clear that Rep. Gifford's assailant, Jared Loughner, doesn't have a coherent thought in his mind, using the term "mind" loosely. So, trying to ascertain some motive by analyzing his "thoughts" is futile for the most part. However, perhaps one of his favorite topics, mind control, is a hint of what's driving him. In his "video" entitled How To: Mind Controller, he states that "If I'm the mind controller then I control the belief and religion." But down below, he indicates that the control extends to action, thought, location, and food, perhaps indicating that besides feeling that his thoughts and actions were being manipulated in general, he specifically felt compelled to go to certain locations and to eat certain things.
In my essays on Andrea Yates, I contend that her actions were controlled by Spirits of Darkness, who were able to take temporary possession of her due to her weak defenses, to the point of overcoming her maternal instincts and forcing her to implacably kill all of her children. I also contend that they targeted her because killing her children, all named after Biblical heroes, was a means of proclaiming "Satan was here."
The attack on Giffords and about 20 other people have this same quality about them - as if the Spirits of Darkness are using some expendable mindless puppet's fixation on Giffords to insinuate their control over his will, and compelling him to commit this inhuman deed. It just has this monstrous quality about it, as if it came from some inhuman being that regards humans as ants and enjoys killing and terrorizing them. This would also explain Loughner's interest in mind control. Note how he claims that controlling someone's "grammar" is a means of mind control - in other words, planting thoughts in their mind. This is one aspect of how the Spirits of Darkness operate. Another aspect is control over their will, forcing them to do something even if there is apparently no human motive.
It's also interesting that the shopping center where Giffords was attacked is fairly close to a ley line, where the influence of these beings would be greater than in many other places.