SharePoint is the first major application to apply Code Access Security (CAS) in a real way. CAS is a great way to protect your Web application from unauthorized code. However, CAS’s implementation in Windows SharePoint Services 2.0 still left a lot of the heavy lifting to the developers and administrators managing the server. With the introduction of Solutions (a specific feature called Solutions) you have the opportunity to deploy code access security when you deploy Web Parts to the server. This article discusses how to work with Solutions.
http://mssharepoint.advisorguide.com/doc/19010 [Website removed]