I think it's pretty easy to tie the shooter to either the right wing or the left wing, depending on your bias.
From the guy's deleted myspace page:
I had favorite books: Animal Farm, Brave New World, The Wizard Of OZ, Aesop Fables, The Odyssey, Alice Adventures Into Wonderland, Fahrenheit 451, Peter Pan, To Kill A Mockingbird, We The Living, Phantom Toll Booth, One Flew Over The Cuckoo's Nest, Pulp,Through The Looking Glass, The Communist Manifesto, Siddhartha, The Old Man And The Sea, Gulliver's Travels, Mein Kampf, The Republic, and Meno."
And there's this:
In a clip endorsed but not uploaded by Loughner, a person wearing a hooded sweatshirt and a black bin liner over his or her legs sets fire to an American flag sitting atop a mound of earth.
It seems he didn't like fiat money (he wanted money backed by the gold standard, a common tea bagger demand, but seemed offended by the "In God We Trust" motto on paper money, which isn't typical tea bagger territory).
Anyone who didn't bring an axe to grind is going to conclude that this guy is crazy.