I'm wondering how far PL/Scope is integrated in SQL developer.
According the book Oracle® Database Advanced Application Developer's Guide 11g Release 2 (11.2): PL/Scope is a feature of SQL Developer. For information about using PL/Scope from SQL Developer, see the SQL Developer online documentation.
But I can't find any trace of PL/Scope in SQL developer.
Are there complete examples to review codes and compare them to a coding standard?
It is integrated. If you are connected to an Oracle 11g Database, and use the View > Find DB Object. This is a normal search if your connected to any database, but uses PL/Scope if you click "More.." wgeb connected to 11g. The More button expands the search to allow you to search for the usage and as such you can search for the variable declarations etc.