Various versions of this trickling in ... from AFP via Yahoo:

The Greek myth that ancient Spartans threw their stunted and sickly newborns off a cliff was not corroborated by archaeological digs in the area, researchers said Monday.

After more than five years of analysis of human remains culled from the pit, also called an apothetes, researchers found only the remains of adolescents and adults between the ages of 18 and 35, Athens Faculty of Medicine Anthropologist Theodoros Pitsios said.

"There were still bones in the area, but none from newborns, according to the samples we took from the bottom of the pit" of the foothills of Mount Taygete near present-day Sparta.

"It is probably a myth, the ancient sources of this so-called practice were rare, late and imprecise," he added.

Meant to attest to the militaristic character of the ancient Spartan people, moralistic historian Plutarch in particular spread the legend during first century AD.

According to Pitsios, the bones studied to date came from the fifth and sixth centuries BC and come from 46 men, confirming the assertion from ancient sources that the Spartans threw prisoners, traitors or criminals into the pit.

The discoveries shine light on an episode during the second war between Sparta and Messene, a fortified city state independent of Sparta, when Spartans defeated the Messenian hero Aristomenes and his 50 warriors, who were all thrown into the pit, he added.

I think we're doing an apples and oranges thing here, no? I've never heard of abandoned children being put in a "pit" (and I don't think the 'thrown off a cliff' is attested either) ... they were simply abandoned on the mountain where, presumably, they'd be taken away by wild animals or -- a recurring motif in ancient stories -- they'd be picked up by some passing stranger.