I wear flats and do the whole minimalist deal. When running easy or barefoot, I land on the forefoot. But when I did a fast session yesterday I noticed that I seemed to be heel striking. This seems to be the case except when sprinting and up on the forefoot.
I thought this was bad, but after a little searching I see that a lot of elites do so as well, even those like Bekele, Gebrselassie, and Sihine:
http://www.iaaf.org/MultimediaFiles/Photo/Competitions/IAAFGrandPrix/21294_W600XH400.jpg
(Tergat)
(El G overpronating)