Based on developer requests for greater flexibility and for better performance, we've added a number of new features for iframe canvas pages that provide them with much of the functionality previously available only to FBML-based applications. These features include:
You can now use FBML tags on iframe canvas pages with XFBML. Many tags, like fb:name and fb:profile-pic, you can incorporate directly into your iframe's HTML. Other important tags, like fb:request-form, you can use within the fb:serverfbml tag, letting you incorporate multi-friend selectors and request forms right into your iframe. If you're trying out Facebook Connect, you might already be familiar with XFBML, and now these same features are available for all iframe applications.
The PHP client library has been updated to combine the new parameters so they can be accessed as part of the fb_params.
We hope that this new functionality will assist developers in creating faster applications for a better user experience. Please send us any feedback and share your thoughts with the community in the Developer forum.