If you’re an OS X Leopard user then you’ve no doubt encountered a dialog similar to this one from time to time:
This means that the file is “quarantined”; it happens whenever you first try to open a file you downloaded via your Web browser.
Generally speaking, this is a good thing, as it makes you think twice about opening something that may potentially be malware. However, if you’re downloading a lot of files that you know to be kosher then it can get quite annoying.
Fortunately, there are ways to disable the quarantine dialog, so that downloaded files open without needing confirmation. I found a good solution over at The Pug Automatic blog – this is basically a short AppleScript that you attach to your Downloads folder as a folder action. Then, whenever a new file is added to the Downloads folder, it’s automatically un-quarantined. Neat.