login for facebook,twitter, and linkedin does anyone has the mod

and i have a question what is the benefit for users being able to login from other social networks on your site ?

http://www.boonex.com/m/Social_Connect_2010_10_30

Speeds up the signup process by taking advantage of existing accounts.

It automatically populates some fields of the Dolphin join form by pulling information from their existing social network account.

Also.. Once the member has created an account on your site & they are signed into twitter for instance they can just click on the twitter icon on your page & automatically login to your site without having to manually enter their username & password.