as far as i know the trap is traditionally set at the end of the first part of the mulsanne straight. and if last years, we might have been in doubt wether the mulsanne-indianapolis section is faster than that or not, i think from 2007 on its obvious again that the first part of the mulsanne is the fastest part of the course, as tetre rouge was heavily modified.
also, i think (but i might be wrong) that the different speeds for each car are caught at different points of the track. if anybody has a more determined position concerning that, i'd be glad to see it
i think it's mulsanne pt.1, mulsanne pt.2, mulsanne pt.3, mulsanne-indianapolis and the last speed would probably be just before entering the porsche curves.