In context of SharePoint, Can you think of the common scenarios or problems where the enterprise design principles or patterns(from GOF or Martin Fowler) can be applied for better solution design. For e.g. The Model-View-Presenter (MVP) pattern is well-suited to the development of server-side Web Parts and Web pages which provide aggregate views.
Also, It will be helpful if you can provide information on the design patterns applied in Sharepoint product itself. For e.g. The Navigation Providers in SharePoint are based on ASP.NET provider model which is an implementation of Strategy Pattern