"if they HAVEN'T been trained to look for certain types of explosives, what is all this Homeland Security crap been about?"

In the case of the security on airplanes, it has all been about getting people to feel safe flying again. It is not about actually preventing terrorist attacks. That is accomplished by spying on potential terrorists, subjecting their entire lives to a full-blown FBI rectal examination, and then arresting them if warranted. (This seems to be working very well BTW.) The fact that the screeners have not been trained until now to find bomb-making materials should dispel any notion that they have been put there for security. They are there to make sure butts are in the seats when the plane takes off.