Visual Studio 2005 Web Deployment Projects provide additional functionality to build and deploy Web sites and Web applications in ASP.NET 2.0 and Visual Studio 2005. This add-in includes a tool to merge the assemblies created during ASP.NET 2.0 pre-compilation, and provides a comprehensive UI within Visual Studio 2005 to manage build configurations, merging, and using pre-build and post-build tasks with MSBuild.
Source: Visual Studio 2005 Web Deployment Projects