I upgraded an ASP.NET MVC2-based web application from autofac 1.4.4 to autofac 2.2.4 today. I hoped that simply swapping out the dlls would be enough, but that was not the case. I found the help I needed on these pages:
Everything worked again after applying the information from those pages.
Update 2010-08-22: I needed http://code.google.com/p/autofac/wiki/WcfIntegration as well, since there have been changes to the WCF integration.