From Facebook Developer Wiki

On March 11, 2009, we introduced the new design for Facebook Pages so that they are more in line with user profiles. Facebook Pages now have two-way communication between the Page and its users.

As application developers, you'll have a chance to have users on Pages engage with your applications in many of the same rich ways that they do on user profiles today.

[edit] Summary of Enhancements

We added new features to Pages. Your applications will run the same way on a Page as they do today. The only change you might have to make is to change the height of your application's profile box if you want it displayed on the main part of a Page.

If you're a Page admin as well as a developer and you want to read about Pages, read the Facebook Pages Product Guide.

Here are the features of the new Facebook Pages design:

• Pages have tabs like user profiles.
  • By default, a Page has Wall, Info, and -- if the Page had added any applications previously -- Boxes tabs. Any application profile box installed on a Facebook Page prior to March 11, 2009 appears on the Boxes tab now. Page owners can move profile boxes between the Wall and Boxes tabs. Pages can have their own application tabs, just like user profiles.
  • Pages can display 6 tabs at a time, just like on user profiles (extra tabs appear in a drop-down menu to the right of the rightmost tab). Page admins can reorder any tabs except the Wall and Info tabs.
  • Users who are fans of a Page will see the Wall tab by default. Page admins can choose which tab to display by default to users who aren't fans of the Page yet. The default selection for Pages created before March 4, 2009 is the Boxes tab. For new Pages, Wall is the default tab since new Pages do not have a Boxes tab until the Page admin adds an application profile box.
  • Pages can use the full width of user profiles for their application tabs -- 760 pixels.
• There are full-width (760 pixel) tabs for most Facebook applications (such as Photos, Video, Reviews, Discussions, Events).
• Profile boxes behave similarly to how they behave on user profiles.
  • Profile boxes that appear on the Wall and Info tabs can be up to 250 pixels in height, and up to 200 pixels wide.
  • In order for a Page admin to add an application profile box to the Page, you call profile.setFBML, like you would for a user profile. If you previously set default FBML for a profile box on a Page, that FBML will be transferred to the new Page design as if you called profile.setFBML. Otherwise, you need to use profile.setFBML to update the FBML as we deprecated the ability for applications to have default FBML.
  • Profile boxes are migrated to the Boxes tab on a Page, like we did with user profiles.

[edit] What We Didn't Change

We didn't change some things for the new Pages design.

• Your application About pages are not changing at this time.
• At this time, the pages.* API methods are not changing.
• Your applications have the same access to user data that is currently available with Pages. For example, you can confirm whether the viewing user of an application tab is a fan of a Page but cannot identify the specific user.
• We still send fb_sig_page_id when a request comes to your application from a Page.
• You cannot run ads in profile boxes or on application tabs of Pages, as with user profiles.

[edit] What's Coming?

We'll release the following features soon:

• Publisher integration for applications on Pages.
• Feed forms so your applications can publish Feed stories directly to a user's Wall from a Page. For now, continue to use feed.publishTemplatizedAction to publish stories to users' Walls and their friends' News Feeds.
• Application info sections that you can render with fb:add-section-button and profile.setInfo.