LINQ Support. LINQ is new feature that adds native data querying capabilities to .NET languages. LINQ defines a set of proprietary query operators that can be used to query, project and filter data in arrays, enumerable classes, XML (XLINQ), relational database, and third party data sources. Queries written using the query operators are executed either by the LINQ query processing engine or, via an extension mechanism, handed over to LINQ providers which either implement a separate query processing engine or translate to a different format to be executed on a separate data store.
As well VS 2008 has design support for LINQ-to-SQL. You have directly database explorer, so that you can create connections and define the matching from your object model to your data model.
Expression Blend Support. Expression blend is XAML generator tool for silverlight applications. You can install Expression blend as an embedded plug-in to Visual Studio 2008. By this you can get extensive web designer and JavaScript tool.
Windows Presentation Foundation. Windows Presentation Foundation which is is a graphical subsystem for rendering user interfaces in Windows-based applications. WPF provides a consistent programming model for building applications and provides a clear separation between the user interface and the business logic. Visual Studio 2008 contains plenty of WPF Windows Presentation Foundation Library templates. By this a visual developer who is new to .NET, C# and VB.NET can easily develop the 2D and 3D graphic applications. Visual Studio 2008 also provides free game development library kits for games developers. currently this game development kits are available for C++ and also 2D/3D Dark Matter one image and sounds sets.
VS 2008 Multi-Targeting Support
Earlier you were not able to working with .NET 1.1 applications directly in visual studio 2005. Now in Visual studio 2008 you are able to create, run, debug the .NET 2.0, .NET 3.0 and .NET 3.5 applications. You can also deploy .NET 2.0 applications in the machines which contains only .NET 2.0 not .NET 3.x.
Built-in AJAX support
Before VS 2008 you have to install AJAX control library separately, but now if you install Visual Studio 2008, you can built-in AJAX control library. This Ajax Library contains plenty of rich AJAX controls like Menu, TreeView, webparts and also these components support JSON and VS 2008 contains in built ASP.NET AJAX Control Extenders.
JavaScript Debugging Support. Because debugging an error in JavaScript is very difficult, now Visual Studio 2008 makes it is simpler with a javascript debugger.
Organize Imports or Usings.Visual Studio contains Organize Imports feature which removes unnecessary namespaces which you have imported. You can select all the namespaces and right click on it, then you can get context menu with Organize imports options like "Remove Unused Usings", "Sort Usings", "Remove and Sort". This is a nice feature to support refactoring.
Transparency in Intellisense drop-down list. When you press the period after some object name, and the intellisense drop-down list appears, then you can hold the Ctrl key to become the intellisense semi-transparent.
HTML JavaScript warnings, not as errors. VS 2005 mixes HTML errors and C# and VB.NET errors and shows in one window. Now VS 2008 separates this and shows javascript and HTML errors as warnings. But this is configurable feature.
Debugging .NET Framework Library Source Code. Now in VS 2008 you can debug the source code of .NET Framework Library methods.
Built-in Silverlight support
Previously developer has to install Silverlight SDK separately, and now this is included in the installation of Visual Studio 2008.
Enhancement to Web designer and CSS support
There is a significant enhancement in the HTML designer to support split-view editing, nested master pages and integration with CSS.