Kent, implantation IS conception.

From Merriam-Webster: 1 a (1): the process of becoming pregnant involving fertilization or implantation or both

From MedicineNet.com: Conception: 1. The union of the sperm and the ovum. Synonymous with fertilization.
2. The onset of pregnancy, marked by implantation of the blastocyst into the endometrium.

A blastocyst has to be implanted to become a fetus, which is "The unborn offspring from the end of the 8th week after conception (when the major structures have formed) until birth. Up until the eighth week, the developing offspring is called an embryo.".

Personally, I think anyone who believes preventing implantation = abortion is nuts, but by the definitions above, preventing implantation IS contraception and 'emergency contraception' would mean RU-486. I don't think they're talking about retro-active IUDs.