A database administrator should have an excellent knowledge of the permission paths required to attach an end user to the use of an object. Coding stored procedures in an application often takes a little more skill than throwing together a quick SQL statement to fire against a server. Such kind of application development can give rise to vulnerabilities like SQL injection attack. Make sure that your front-end developers are aware of the ins and outs of these attacks. They can be your best friends at securing data.
At the same time, you should always apply security patches expeditiously to your SQL Server environments. Exposure to the web and to e-mail attacks are only going to increase over time. Finally, stored procedure encryption does have both viable uses and weaknesses. If properly implemented, it can be a great help in securing your business rules.