The presence of a left-leaning academia is fairly accepted both from those inside and outside the university setting; the importance and relevance of this, of course, being a different issue. And while there is a fair degree of criticism leveled at professors who take their politics a bit too far (even if protected as citizens under the First Amendment), the fact that these same people are the ones writing the textbooks is rarely extrapolated to suspicion of the textbook industry.
Fox News Network has undertaken a series exploring bias in school textbooks, with a segment airing yesterday focusing on treatment of the War on Terror. I'm skeptical of allegations of bias in general -- for example, Cindy Sheehan does symbolize a very important aspect of the war debate, regardless of your view of her -- and when the charges include biases of omission, such as the failure to cover this or that war hero, the argument becomes even more tenuous.
In this specific case, I'll let you be the judge. Regardless of your conclusions on this specific issue, the segment certainly sheds light on an issue that has avoided scrutiny for far too long.