The new feature means that Yahoo Mail users can now connect their Facebook accounts and integrate their Facebook friends' e-mail addresses into their Yahoo Contacts list. Users can visit the Import Contacts page to be guided through he Facebook friend import process.
Of course, this is just the beginning of the full Facebook Connect feature bonanza on Yahoo. You can expect functionality to be integrated into News, Sports, Finance and even Flickr in the months ahead.
Given that Facebook is now 400 million members strong, we have to believe that there's a significant shared user base between Facebook and Yahoo. In a perfect world, Yahoo will see those users stay on Yahoo properties and use the Facebook contact and sharing functionality to push Yahoo content out to the world's largest social network and generate more traffic in return.