DesktopServices in Apple Mac OS X 10.6 before 10.6.3 preserves file ownership during an authenticated Finder copy, which might allow local users to bypass intended disk-quota restrictions and have unspecified other impact by copying files owned by other users.
http://support.apple.com/kb/HT4077
http://lists.apple.com/archives/security-announce/2010//Mar/msg00001.html