While column view has featured a preview since the public beta, Jag's new feature lets you see an entire folder previewed at once. This can be quite handy when browsing through a directory of scanned art, stock photos --- or, more commonly, pondering whether to delete photos emailed by your photo-prolific relatives.
[Editor's note: Unfortunately, it seems the previews created in Folder view do not carry over to Column view. I spend about 99% of my OS X time in column view, so I tested on a folder full of generic ".gif" icons from a current project. Switching that folder to icon view and setting the "Show Preview" did, indeed, instantly show the nifty preview icons -- very cool!. But when I looked at that folder again in column view, I still had the generic icons (unless I clicked the actual object to show the preview column). So I'll still have to use pic2icon to give me a "sneak peek" at the image without activating the preview column.]

