Problem
As from SCCM 2007 SP2 it is not required to have a certificate anymore when you are configuring Asset Intelligence.
However, when you configure it, the console still reports the error that a bad certificate has been found. 
Cause
This issue occurs because the bootstrap certificate has been expired on the 24th of April 2011.
Resolution
There is a hotfix available to solve this issue: http://support.microsoft.com/kb/2483225/