Last year there were rumors that Facebook was going to make a drastic change to the way Facebook Pages are displayed. Looks like the rumors were right. As of August 23rd your Facebook Page is going to be limited to 520 pixels. This might not sound like a big deal to Personal Profile owners, but for Facebook Page owners this could be an expensive and time consuming issue. Many Real Estate Agents and Brokerages have put a lot of time, effort and $$$ into creating custom "Facebook Page Landing Tabs" using FBML (Facebook Markup Language, a Facebook application). I myself have created 5 or 6 of them for my clients, luckily the ones I created were pretty basic and easily changed to fir the new requirements.
If you do have a Facebook Page, take a look at it. Facebook has started displaying a banner message and gives you a preview of what your Page will look like then the change occurs. Hopefully you're ok and if not you better get it updated!
According to Facebook the changes are based on feedback they received:
“These updates are designed to simplify navigation for users, reduce complexity for developers, and enable us to build the next generation of tools for growing your business with Facebook. We’ll share more of our plans for the roadmap in the coming weeks.”