First the facts insofar as I am able to find, then my opinion.
Although 36 of 50 states have bans on late-term abortions they are still performed routinely. We must concede that any such attempt to put a number on this is fraught with statistical peril due to the fact that abortions are covered under privacy laws. However, just to get a general feel - Wikipedia cites that the CDC believes that some 1.4% of all abortions are performed late term or after 20 weeks. If this is accurate then the best estimates would indicate that some 700,000 late-term abortions have been performed in the US since roe v. wade.
Now my opinion: The 700,000 figure is based on nearly 50 million abortions performed since Roe v. Wade. Although this exact figure is disputed heavily by both left and right wing sides of the argument they both generally agree that some 25 - 33 percent of all pregnancies end in abortion. If you consider that 11 million people died in the Holocaust the math necessitates ought give even the coldest of individuals pause to consider at what point an embryo is a baby - i.e. a human being. Such inquiry is the same sort of foolishness that slave traders were guilty of, namely, marginalizing the humanity of a people group they don't understand.
So, my opinion, put bluntly. It's murder - it is always murder. Concerning the posters: be offended by the pictures, that's the point. It may seem tasteless but it is done for the reason that we remember the Holocaust. The difference in this case is that the conflict is not obscured by history or geography, but imminent.