This one wins my "Stupidest OS Design of the year award, and it's not even Vista related. it's actual Mac OS Related. yep!
"Perhaps the most troublesome of the problems has been a data loss issue caused by Finder, which performs a function on Macs similar to that of Explorer in Windows. In Leopard, when Finder moves a file from one drive to another, it deletes the file from the originating hard drive, without first checking to see if the file arrived safely on the destination hard drive. If anything goes wrong during the file transfer, such as a momentary power glitch on the destination hard drive, the file would then be destroyed on both hard drives."
Update: To all those who think this issue was fixed - here's the quote from the article:
"Leopard users hoped that a free maintenance update (OSX 10.5.1), released on Thursday, November 15, would fix the issue, but Apple's statement accompanying the update is too vague to give a definitive answer. With regard to data loss, it states that "... a potential data loss issue when moving files across partitions ..." has been fixed, but moving files across hard drives is not addressed. Personally, I wouldn't want to bet my important data on that statement."