to those who are unsure as to how the files will arrange themselves, note that panther is said to use extensive 'metadata'. this is similar to how iTunes can sort your files by bitrate, filesize etc, but it will be in the finder. piles are simply like 'smart playlists' in itunes, that accumulate and remove files according to criteria you set for each pile. imagine a pile with your "25 most used documents" or "Jpegs larger than 100kb, created after 12/03/03, used in the last month" etc. imagine the possibilities.
now, i'm sure most of you don't use your smart playlists in itunes very often, but such a feature in the finder will have a different order of functionality.
finally, to those worried about expanded views of piles going off the screen, just imagine that only 1 file is fully spaced out between the others, and the distance between floating icons decreases as you look above/below your cursor. imagine each pile is like a dock with magnification turned on, only vertical, and the sizes of the icons don't change, only the distance between them.
to those worried about older computers having difficulties with previewing the files within a pile, just imagine that each image has its preview BUILT IN to the icon. currently, for most images, the previews are generated 'on the fly' in Jaguar. this eats up processing power and places more demands on the hard drive, taking more time. this would cause piles to 'stick' when they are opening. if every file (ie images, text) had a small preview BUILT IN to the icon (or into its associated data), this would allow much faster performance. imagine that whenever a file is created, this preview is saved along with it. this can also apply to movies with a few seconds of a low res (128 by 128 max) preview movie. sure, this will add a little to file size (a REALLY tiny bit) but it will be worth it. of course, as in the current finder in column view, you will be able to see the full, larger previews such as movies at full size (in piles, when your cursor actally passes over each file), and this information will have to be taken from the file itself (on the fly). but the icon image/movie previews will be prerrecorded.
on another note, what do you think about putting more maginification in the finder in general? like waving your cursor over some small icons in a finder window and having them magnify?