@BrettC
"as I discovered after seeing @Whiteman007's video post (thanks!) - at least in my case the messed up icons are triggered whenever I save a file from some app and the Save/Save-As dialog box pops up, as I mentioned"
Yup, I notice the most annoying Finder re-arrangement happens to my certain folders in my Documents folder and Downloads folder. Usually it is after *something* has written to it. Eg. saving a document, or downloading something.
The Save/Save-As dialog box messes up some Finder settings for that folders that you navigate through. It is not the only culprit though, just downloaded Chicken Of The VNC for example, dragged it to Applications etc, and viola, Downloads folder was messed up this morning even though there was no "Save/Save-As" prompt since Safari puts it in Downloads automatically.
At least I think we narrowed down the bug a little. Hopefully anyone with Developer accounts reading this and trying out 10.7.2 can test this out further.
Personally, somewhat dissapointed that the Finder has gone "off" after doing so well in Snow Leopard particularly with the Cocoa rewrite in SL.
Edit: Don't get me wrong, I think the two options of "Arrange By" and "Sort By" are good. It's just that these settings seem to be messed up when something "touches" the folder.
Tip: Cmd-Option-1 or Cmd-Option-2 (Clean Up By...) keyboard shortcuts. The best thing to do for now if you see a folder in which you don't like the arrangement. Just hit those keyboard shortcuts and the pain goes away for a while đ