A new set of rules was released yesterday for the following tools: ExBPA and Disaster Recovery and Performance Troubleshooter.
What is contained in the update?
The update contains mainly bug fixes for the above tools.
The BPA tool is also run automatically during setup and readiness checks. We have updated the prerequisites XML file for setup. So any Exchange setup launched on a machine connected to the Internet will download the updated prerequisites file to check for the correct prerequisites.
Read more at source: http://msexchangeteam.com/archive/2009/01/07/450370.aspx