While users of Facebook apps built in FBML have been able to post content to friends’ feeds for quite a while, Facebook hasn’t supported the same functionality for iframe apps or Facebook Connect-enabled websites.
However, that’s changing today. Now, iframe apps and Connect websites will be able to use showFeedDialog to publish content to one friend’s wall. However, to publish content to multiple friends’ walls, developers will still need to use the FBML multiFeedForm.
Allowing users to post content (like gifts) to friends’ walls can be a powerful way for applications to grow virally. Profile pages are highly trafficked by friends and stalkers, and feed stories get syndicated to the News Feed for further distribution.