The company  refers to it as an alternative to Facebook Login (which is the current name for Facebook Connect), when you want to provide an option for users without Facebook accounts, your site needs additional info that Facebook doesn’t provide, or a traditional HTML form suits your site more. 

"For users who are logged into Facebook, the registration tool will pre-populate fields with information they’ve already entered on Facebook, saving them time and specifically showing what information the website is requesting," the rep explains. "Nothing will be shared with the website until the user decides to connect and click ‘Register’."

 "Website owners can also customize the fields to ask for additional information, which the user can enter without sharing any information back to Facebook," she adds. "Once an account is created, the site will become customized for that person, filtering content based on the actions of their friends, such as comments, reviews and likes."

The tool actually has the potential to increase conversion rates (possibly e-commerce sales). 

"By minimizing the friction associated with signing up for a new account and making it easy for people to bring their friends with them, we’ve seen that people are more likely to complete the sign up process, stay on sites longer, share more content and come back more often," says Facebook’s Paul Tarjan. "For example, in beta tests with FriendFeed, Facebook sign ups increased 300%."

This will no doubt be an attractive offering for a lot of site owners, considering how important the Facebook-hosted social graph is becoming to the web. If it can increase conversions and it only requires a single line of code, lots of sites will likely jump on board.

Websites place content behind forms for the purpose of collecting information from a visitor requesting access to it. The site publisher might want those details for demographic details to improve marketing campaigns, for example.

Google thinks it can present better results to searchers by having access to the URLs behind forms, improving the site’s exposure in the process. The Google Webmaster Central blog promised their crawls will be well-behaved:

Only a small number of particularly useful sites receive this treatment, and our crawl agent, the ever-friendly Googlebot, always adheres to robots.txt, nofollow, and noindex directives. That means that if a search form is forbidden in robots.txt, we won’t crawl any of the URLs that a form would generate. Similarly, we only retrieve GET forms and avoid forms that require any kind of user information.

However, concerns have been raised about Google crawling forms not marked as forbidden. Kevin Heisler complained at Search Engine Watch the practice could violate the privacy of corporate data.

Though confident in Google’s intentions, Heisler thinks potential backlash from corporate interests could be a problem. “The costs to CEOs, CIOs and CTOs at corporations far outweigh the benefits to consumers,” he said.