This tip works from all apps… Just set the Safari pref and you are good to go. Seems silly that Apple would not have noted this functionality within the pref itself. The way things are worded would lead you to believe that the page you are on would be replaced with the new request.
I’m using the latest version of Safari (1.0b2, v73).
Here’s a tip for NetNewsWire users: if you want links to open in new tabs in Safari, do this in Safari’s preferences:
1. In the General preferences, at the bottom, click “Open links from applications in the current window.”
2. In the Tabs preferences, click Enabled Tabbed Browsing.
Then, when you’re opening links from within NetNewsWire, each one should open in a new tab in Safari. [inessential.com]