The Clustered Index is not the Primary Key

I was reading through a list of links for Database Weekly and ran across this script from Pinal Dave, looking for tables where the clustered index isn't the PK. It struck me that this is one of those facts I consider to be so simple, yet I constantly see people confusing. If you click the Primary Key icon in the SSMS/VS designers, or you specify a PK like this: "The Clustered Index is not the Primary Key"