Actually that's not technically accurate. Non-clustered indexes will have all the key columns of the clustered index, but that does not have to be the PK. Indeed, best overall performance often demands that it not be. For example, you might cluster by ( datetime, location, ident ) or by ( location, datetime, ident ) but have ident alone as the PK.
SQL DBA,SQL Server MVP(07, 08, 09) "It's a dog-eat-dog world, and I'm wearing Milk-Bone underwear." "Norm", on "Cheers". Also from "Cheers", from "Carla": "You need to know 3 things about Tortelli men: Tortelli men draw women like flies; Tortelli men treat women like flies; Tortelli men's brains are in their flies".