I'm wondering if it is possible to add the user registration plugin with the Facebook/Yahoo/Google/Bing/Twitter account details for seamless login.
See http://mashable.com/ top right corner.
There is no specific integration with any of those services in the User Registration add-on. I'm not sure how you would integrate the two. If it's possible, it would be a customization outside the support we can provide here. It's not a feature of the Gravity Forms User Registration Add-on.