One of the world's largest drug store chains is employing a very unusual---and provocative---method for sourcing its drugs.

This week mighty Wal-Mart found itself at the center of a street-level drug deal that raised larger questions about where and how the retailer gets its cheap drugs.

In June of 2008, I wrote in this space about Wal-Mart's global sourcing empire for prescription drugs, quoting one pharmaceutical industry analyst...