It says it very clearly here: http://msdn.microsoft.com/en-gb/library/ms188351.aspx
"Changes the name of a user-created object in the current database. This object can be a table, index, column, alias data type, or Microsoft .NET Framework common language runtime (CLR) user-defined type."
"Renaming a stored procedure, function, view, or trigger will not change the name of the corresponding object name in the definition column of the sys.sql_modules catalog view. Therefore, we recommend that sp_rename not be used to rename these object types. Instead, drop and re-create the object with its new name.
Renaming an object such as a table or column will not automatically rename references to that object. You must modify any objects that reference the renamed object manually. For example, if you rename a table column and that column is referenced in a trigger, you must modify the trigger to reflect the new column name. Use sys.sql_expression_dependencies to list dependencies on the object before renaming it."