So since this has been a hot topic amongst us vacationing parents, I did some research as to what ACTUALLY happens if/when you take your child out of school for "unexcused" absences, (at least in the state of NY).
Child Protective Services can contacted by the school district to investigate for educational neglect, however, there is well-defined criteria that has to be met to actually PROVE that educational neglect took place.
I'm friendly with a local CPS investigator, she says that unless the school (here locally) thinks it's foul play (abuse or parents don't know etc), they don't request an investigation. They are costly and long and usually are unfounded because it doesn't met enough of the criteria set forth in the law.
Bottom line? Huge scare tactic on the schools behalf. I agree kids need to go to school, but I won't be intimidated if they are physically with me then that's my choice.
Here's some light reading if you're bored:
http://www.p12.nysed.gov/sss/pps/educationalneglect/