simnow@amd.com is a very old email. The email to use should be simnow.support@amd.com. If you ran accross simnow@amd.com somewhere amongs the SimNow documentation, please let us know and we will update the documentation.
SimNow is still a supported tool, and the last Public release to developer.amd.com was done in June 2010. See the dowload links at the bottom of http://developer.amd.com/cpu/simnow/Pages/default.aspx. We anticpipate another release this year with support for platforms using Fusion APUs.