Facebook won't let you link from an iframe page to another part of Facebook (without opening a new window). This plugin gives you that ability.
Makes it possible for a WordPress page viewed in a Facebook iFrame to link to other Facebook content, such as the Facebook wall or a photo album. (Currently, Facebook disables an iFrame app's link to other Facebook content as Facebook will not display itself within its own iFrame.) This overrides that by adding a target property to all links to Facebook content.