L' Eomot Inversé (10/19/2012)
Actually, there's a misprint in the question (my stupid error) - it should say @ROWGUIDCOL, not ROWGUID. You can have as many rowguid columns as you like in any kind of table (just as you can have as many int columns as you like in any kind of table - after all, rowguid is a type like any other type), but only one of them can have the ROWGUIDCOL property (just as only one column can have the IDENTITY property). I'll ask Steve to correct that wording (and 2011) if possible.
I disagree with this. Yes, the question was technically not completely accurate. But your explanation here is worse. The term "ROWGUID" does not exist in SQL Server. It is not a type like any other type. uniqueidentifier is a type like any other type, and the commonly accepted short form for that data type name is guid. Not ROWGUID.
To me, it was obvious that "ROWGUID columns" was intended as "columns with the ROWGUIDCOL attribute. Especially since "ROWGUIDCOL columns" would have sounded redundant.