How to Suppress Repetition of Warnings That an Application Was Downloaded From the Internet on Mac OS X?

"To remove the quarantine alert you can run the following command in Terminal:

xattr -d com.apple.quarantine /PATH/TO/APPLICATION

You may need to run this is an administrator depending on the permissions on the resulting application (as you said you don't run as administrator). If the application has permissions set that you can't remove the metadata with your user account it explains why it comes up every time. You can either run it as an administrator on your computer or run the command above as an administrator. (Use su admin_name if necessary)"

"http://www.macosxhints.com/article.php?story=20071029151619619

A Vista-esque feature of OS X 10.5 is that it tags web downloads (not just those from Safari) as such, and then warns you about running downloaded apps. Archived (e.g. zipped) files inherit the tags from their tagged container.

Link is to discussion of issue and a few scripts and C++ strings you can run to change the behavior permanently.

Not sure if these are going to work with 10.6"

"This has been an intermittent problem since this question was first posed here, but with Lion it has become commonplace. After a restart of the OS the ""quarantine"" question will be asked again. Once answered it will not be asked until the next restart.

It's clearly a bug. I suspect it occurs when cautious/smart users run as a non-admin user. It may be related to doing the initial install from the admin account.

We can either live with the bug until it's fixed (not a bad solution) or, if you really can't stand it, I prefer this fix for Lion (example of app shown here) -

OS X should have flagged after you clicked open. You can remove the
quarantine flag manually. Open Terminal and paste the following
command:

sudo xattr -r -d com.apple.quarantine {,~}/Library/PreferencePanes/Screens\ Connect.prefPane/Contents/Resources/ScreenSync.app"