How can I disable Mac OS Lion asking if I really want to open a downloaded file? I already tried this:

cd ~/Downloads
find . -print0 | xargs -0 xattr -d com.apple.quarantine


But it doesn't seem to work under Mac OS X 10.7 (aka. Lion) anymore:

xattr: ./cabin/Cabin-Bold.otf: No such xattr: com.apple.quarantine
I haven't tested this under Lion but 

defaults write com.apple.LaunchServices LSQuarantine -bool NO


and then restarting should totally disable this functionality.