Ronald Reagan who defined the term conservative for a generation was occasionally accused of not being conservative enough and liked to joke that sometimes his right arm didn't know what his far-right arm was doing. It was the kind of joke that let his friends on the far, far-right know that while he liked them all right, since he was in the business of governing he'd have to make strategic compromises from time to time that they wouldn't like. You've got to figure that Reagan would be chuckling at the prospect of conservative politicians being challenged from the right in GOP primaries this year.
In Texas, conservative Governor Rick Perry, regularly ridiculed by Chris Matthews for being for secession is being challenged from his right by Debra Medina. In California, Congressman Gary Miller's 91% conservative voting record in '09 from the American Conservative Union has not prevented him from getting a challenger from his right flank either in the form of CPA Phil Liberatore who complains that Miller bucked his party and voted for a large-scale federal response to the housing crisis.
Whether or not these challenges are successful, they are likely to have an affect on Miller, Perry and other established politicians as they face the wrath of at least some voters, inspired by the Tea Party movement, who believe they aren't conservative enough.