Is there any script based on ZF, which supports normal user signup/login system, along with user authentication throuh Twitter and Facebook.
Have a look at An example of OpenID, Facebook and Twitter authentication in Zend Framework 1.11. Altough, the application does not show how to use normal user authentication (it was not the purpose of it) it shows one way of using OpenID (Google, Yahoo, MyOpenId, AOL, OpenId) as well as Facebook Connect and Twitter Oauth for authentication of users. This is more difficult to do in ZF than regular user authentication.