In that spirit, you should read Melissa's brief post on babies and original sin.
I was up in NJ this weekend for my nephew Liam's baptism. The Catholic rite is very clear about naming the cleansing of original sin as one of the primary effects of baptism. Augustine's thought has obviously been preserved through the liturgy and doctrine of this sacrament.
Melissa has identified beautiful imagery of Augustine's in order to point out that babies' theological "meaning" should not be confined strictly to their proving the doctrine of original sin. But what I like about her commentary is that it doesn't necessarily preclude or rebut the doctrine of original sin. In Augustine's thought, both images were true: the self-centered baby with the corrupt will, and the helpless, clinging, loving baby, nourished only by God.
In fact, it may be precisely because of the first image that the second image is so meaningful. If we were not thoroughly corrupted by original sin, then the helpless and dependent baby would not be a fitting metaphor for our spiritual state. If we were not corrupt in this way, we would not be utterly dependent on God's grace; we could save ourselves. So in a sense, the baby clinging to the mother can be seen as just as much of a refutation of Pelagius as is the baby who cries until its physical desires are met.