Like Facebook Connect, the service allows other sites and applications that are already integrated with Twitter to authenticate users more easily. While many Twitter applications already allow users to log in using their names and passwords through the Twitter API, the new feature offers a more secure alternative because third-party developers don't handle passwords.
That should help the micro-blogging service increase trust with its fast-growing user base, according to the Inside Facebook blog, as it builds the latest platform connecting the social Web.--Mark Walsh
Twitter's API is powerful but not a client service like Facebook Connect. Advertisers and publishers can now implement both Twitter and Facebook Connect through a single, free API service called Gigya Socialize. http://gigya.com/Content/Socialize.aspx