Unfortunately, children younger than pre-adolescent age are being sexualized in such a way that this becomes a debate on the disboards. I can understand those that are concerned with the "predator" angle but like one poster said, there is little we can do but to keep on eye on our kids. This isn't exactly what was said but I think it was the gist. I think about these things too but never let my children at that age be without the supervision of an adult.
I am one of those parents that has let my daughter go swimming or jump in puddles or whatever in her underwear when we've been caught off-guard and without swim clothes for whatever reason. I also let my son (probably around 2 or 3 years old) swim butt naked in the ocean quite often because he took the suit off quicker than I could get it back on. I had one woman at the beach threaten to call social services because I removed a diaper, rinsed my sons bottom off in the water (it was not soiled, only sandy) and then dressed him. I think he was all of 2. God forbid her little angel at age 2 or 3 should see him naked. BFD!
Those of you that are afraid that your little girls (or little boys for that matter) might be damaged for the rest of their lives because they see a naked child, all I have to say is, OMG! Children mimic their adults and will make the naked body something to be ashamed of and to hide. I personally get a good chuckle when I see the dimpled bum of a little one
I am not advocating that preteens or adults run around naked but we are talking about children and babies. Let's let them be babies and children! The freedom of being naked can only be enjoyed for just so many years
And for the posters who mentioned their daughters bearing their naked "pre-breasts"

instead of wearing slutty looking bikini tops -- I could not agree more! Kudos to you for recognizing that one is natural and the other is sexualizing their bodies and there is a HUGE difference