In my Macbook (Lepard: OSX version 10.5.8), Safari (version 4.0.4) in general opens a new link in a new window instead of a new tab if the link has
target="_blank" attribute. It just gets in my way of organizing things.
To force the link open in a new tab use the following command (without my favorite prompt sign “$”) in the terminal and restart Safari:
$ defaults write com.apple.Safari TargetedClicksCreateTabs -bool true
Notes: 1. This will open the link in the foreground. Command+click will however open the link the background (even without the above trick).
2. Change `true’ to `false’ to revert back to the default behavior.
Credit: MacOSX hints.