White stuff in my peaches
Here's what I found on ehow.com
In some ripe peaches, white spots may appear in the pit and/or the area around it. Although these spots resemble mold in appearance, they are actually naturally-occurring. Called callus tissue, they are not mold, fungus, bacteria or the result of any type of disease. These spots are entirely safe to eat along with the rest of the peaches that they appear in.
I did find this after some Googling - might it be what you're talking about? Seems like it might be a natural insect- and disease-control spray they use (one that both conventional and organic growers are using). I'm assuming if this *is* what you're talking about, the spraying might be done early in the season when the peach trees are budding, so some of the particle film gets inside the peach.
OK...I don't actually know what it is, but I'm positive it won't hurt you. I live in peach growing country (upstate SC). As a child I would walk across the back yard, into the neighbor's orchard, and eat peaches off the tree. The white stuff is often present, so it's definately not a sign of the peach not being fresh.
I'll try to post a more intelligent answer if I can get my Mom to elucidate me.