The vanilla deployment product in Visual Studio.NET 2005 was lacking in support for more advanced deployment configurations/options beyond the core "Publish Web" scenarios built-into VS 2005 – specifically around assembly naming/output, advanced MSBuild customization, and other common scenarios. (for example: the ability to modify connection string settings depending on the build configuration, etc).
Therefore, Microsoft has shipped on the web a new free add-on to Visual Studio that enables what we call “Visual Studio 2005 Web Deployment Projects”. This add-on provides a lot of additional deployment features and capabilities that complement the built-in web project support in the product.
You can download the beta of Web Deployment Projects and read the MSDN whitepapers that will document it more exhaustively over the next week as well from http://msdn.microsoft.com/asp.net/reference/infrastructure/wdp/default.aspx.