First off, we have a new article over on PHPBuilder.com (finally) about working with Postgres on RedHat 7.0. They talk about how to set it up, how to tune it a bit and how to set it up so that you can use it. Nice general setup tutorial.
Also today, DevShed has an article that, while not completely PHP related, does have a section on PHP and Cybercash in it. Their newest article, Script-Based Credit Card Interfaces talks about some of the common interfaces and how to build a sample interface to one. They also cover some of the privacy and security concerns that should be addressed.