The spectre of individual or loner direct action has been around for a long time, often called the 'Lone Wolves' or Lone Attackers by analysts.

See this recent commentary:http://raffaellopantucci.com/2010/12...one-attackers/

What motivates such people remains elusive; much of the commentary I've seen concentrates on the internet's role in radicalisation and preachers of hatred.

The comments by the local Sheriff no doubt will echo around for awhile:
We have become the capital, the mecca for prejudice and bigotry.
Link to Sheriff's press conference:http://www.blogforarizona.com/blog/2...g+For+Arizona)