I have seen a number of other cartoons about Obama's upcoming speech to students. Most contain themes similar to this cartoon. I'm personally not aware of any parent referring to the president as a Nazi (although the Speaker of the House earlier referred to health care opponents at town hall meetings as carrying swastikas!).
Most parents are concerned about the politicalization of the speech. True, presidents have often talked directly to students...usually about the importance of staying in school and learning. No argument there. However, this is the first time that I've heard of a president asking students to submit essays to help him run the country. I thought he already had a plan!
Many schools are letting students "opt-out" should their parents wish that they not be exposed to the speech.