I know Gilbert's very interested in different payment gateways, too. You should also give thought to whether or not you can provide a reasonable abstraction that can cover manual settlement (i.e. encrypted e-mail of order information followed by manual credit card verification).
It would be great to have payment services separated from e-commerce, since e-commerce is only one package that might make use of such a tool.
Another obvious client would be an events package, or components of a dotLRN solution where on-line registration
might be allowed, etc. Or donation handling for non-profits. The potential list is lengthy and payment services should be a central service of the toolkit.
