The New York Times has a compelling, thorough account of the rise of the Tea Party movement, its spread through media figures like Alex Jones and Glenn Beck, and its connections with preexisting radical groups like the John Birch Society and the militia movement. (The John Birch Society will co-sponsor the 2010 Conservative Political Action Conference, which attracts leading Republican figures.)
The article is an important marker in the slowly disappearing line between mainstream Republican politics and the paranoid far right, and well worth a read.