We have released a new plugin that supports the hosted payment form offered by Authorize.Net.
This method of accepting Credit Cards is the safest way to go, no credit card information is entered on the NopCommerce site, it's all entered on Authorize.Net's servers.
NopCommerce V2.8 and 3.0 are available now. Working on 3.1, 3.2.
It's available on our third party site at http://www.Effective-Systems.net.
We also have posted free fixes there for the USPS changes that happened back in July of 2013 that caused the NopCommerce plugin to show gibberish instead of the trademark and copyright symbols. (NopCommerce v2.6 and 2.8 plugins fixed and available in compiled form)
We are also offering a free version of the PayPal Standard plugin that has an enhanced admin panel that allows for configuring some additional parameters that were causing issues with PayPal rejecting a payment attempt. (available for NopCommerce V2.8)