Actually, Palin really shouldn't have endorsed anyone in the California U.S. Senate Republican primary. Reason being is that it has predictably caused a riff among her supporters in California, many of whom are rightly suspicious of Carly Fiorina's conservative credentials. The fact that Fiorina was an advisor to McCain's presidential campaign and Chuck DeVore is the only bona fide conservative running in the GOP primary (who has as good a chance of beating Barbara Boxer as Fiorina and Tom Campbell) suggests that Palin's endorsement is less than sincere. I, myself, asserted in the com-boxes at the Conservatives4Palin blog that Palin's endorsement amounted to nothing more than cynical payback to McCain (oh, the flak I got for that!). Further support of my assertion can be seen in Palin's endorsement statement where she mischaracterized Fiorina's father as a humble "schoolteacher" of children (the late Joseph Sneed was a law professor at both Cornell and Stanford, and later the law school Dean at Duke).
Will this endorsement by Palin come back to politically hurt her? Maybe. At least in my eyes, though, her credibility as a principled conservative has been diminished.
Update: I just caught this from Palin's update to her endorsement of Fiorina: "And most importantly, Carly is the only conservative in the race who can beat Barbara Boxer." The issue of whether Fiorina is a conservative aside, Palin's assertion is most surely incorrect, as the Rasmussen poll I linked to above actually shows DeVore slightly ahead of Fiorina in a head to head contest against Boxer.