The answer to this was a "try it and see" one.
With the Finder window active, go to VIEW and select "Show View Options"
Click on "Show Icon Preview"
Bingo, your PNG's now become small pictures.
How dat?
P
I was just watching the Apple Quicktip "Snapshots" episode, and I noticed that on the video, when a snapshot was taken and the png file was saved to the desktop: the icon was a thumbnail preview of the real image.
On my mac, I just get the generic PNG icon.
Why is this?
Alex

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic