Brad, the Verisign module is great replacement for the old CyberCash module. However, the OpenACS 4.x ecommerce module will soon be modified to work with payment gateways based on a service contract. Please search the bboard for 'CyberCash Verisign Authorize.net' (
https://openacs.org/bboard/search-entire-system.tcl?query_string=cybercash+versign+authorize.net&submit=submit) for parallel threads with more information.
An alternative gateway to Versign based on the above service contract is in the works. A gateway to Authorize.net is not far of either. It wouldn't be too hard to wrap your Verisign module in the service contract (when the payment service contract get's published) thus making the module available to all other packages.
The securenetshop (http://www.securenetshop.com/) is indeed a full featured alternative to the ecommerce package offering features the ecommerce package is lacking. However, the disadvantage of securenetshop is that it lacks integration with the OpenACS database.
With the use of more service contracts we could split off many of the features of the monolithic ecommerce package into separate packages. Like the payment gateway, shipping rate calculations and search can be handled by service contract based services. While it will take time to accomplish all this, it does create a more flexible system. One could even have several ecommerce packages each tailored to different needs.