We have developed facebook application from 2007 and we have seen the changes of the framework, many updates and version of the sdk. But there is an other thing that as Facebook developer we need to pay attention to, the platform policy. We have witness Facebook pages and applications sunddently disappeared. Some may come back after filling the appeal form and do some adjustments. Some have gone for ever.
Some links the worth to read:
Facebook Principles and Policies: http://developers.facebook.com/policy/
Policy Examples and Explanations: http://developers.facebook.com/docs/guides/policy/examples_and_explanations
Developer Forum: http://forum.developers.facebook.com
Statement of Rights and Responsibilities: http://www.facebook.com/terms.php
An other tip, if you developing your facebook application, please keep in developer mode and also note that facebook has introduce a new feature for you to create test account: