I read on this thread (https://forum.virtuemart.net/index.php?topic=59546.0) that authorize.net CIM integration is possible, even easy, but the thread linked to as support doesn't seem to provide a clear answer. Additionally, someone who is apparently a VM developer states here (http://community.developer.authorize.net/t5/Integration-and-Testing/Bulk-transactions-with-authorize-net-and-Virtuemart-Shopping/m-p/2239/highlight/true) (last post in the thread) that CIM support may be coming 3rd quarter 2010 (which would mean it's here by now I guess). Just wondering if anyone knows whether or not the CIM integration can be done in VM 1.1.5? Thanks.
I answered my own question by getting in touch with the gentleman who posted in the second thread to which I linked above. He is a third-party developer whose company is looking at doing a CIM module in the near future. Obviously, the feature is not supported by the core :)