Following are Walt’s picks for additional resources that you may find useful.  Each has its own personality and focus. 

http://www.educause.edu/pcidss 

Educause is Higher Education’s dedicated source of IT and security information.

http://www.pcianswers.com/

This is the PCI Compliance Demystified blog.  It is widely read by security experts and is a respected PCI blog.

http://www.forum.pcianswers.com/ 

This is the PCI Forum is an extension to the pcianswers site.  Here you can ask and answer questions.  There are over 80 threads going at any one time so it can seem a bit daunting, but a number of PCI practitioners visit here both to ask and answer questions.

http://www.robnewby.blogspot.com/

A good security and PCI blog with a bit of an international flavor: the editor is British working in Spain. 

http://www.riskanalysis.riskmanagementinsight.com/

As the title proclaims, this is “A Weblog for Risk Geeks.” 

http://www.securitycatalyst.com/

The Security Catalyst is a security site “helping to change the way people think.”  The discussions are thoughtful and the participants are on a mission.