Apparently, a couple of airlines from down under (Qantas and Air New Zealand) have policies that prohibit men from sitting next to unaccompanied children. The presumption, of course, is that the men might somehow endanger the children.
Now, it's true that the vast majority of child molestations are committed by men (though you have to wonder how many of them happen on planes), but as the article below discusses, such a policy presumes all men to be potential child molestors and discriminates against them.
Airline seating policy may breach Human Rights Act - 30 Nov 2005 - National News