The list below is not in order of importance, instead it is in the order I suggest you explore this new release.

1. VS2008 and Fx 3.5 will officially launch together in February but will be available to developers by the end of November 2007. The same type of Visual Studio SKUs/Editions available with VS2005 will also be available with VS2008 including a brand new one: VS2008 Shell. VS 2008 is a great Vista client, has better aesthetics and a bunch of new usability features including enhancements for multithreaded debugging.

2. Fx 3.5 continues with the additive approach that we introduced with Fx 3.0 while still not introducing a new CLR. As a reminder, Fx 3.0 simply added to Fx 2.0 without changing or removing anything in the existing assemblies (it added WPF, WCF, WF and CardSpace). So, Fx 3.5 simply adds some assemblies to the existing set of DLLs that Fx 2.0/3.0 comprises of. This means that simply installing the framework should not affect your existing solutions. Note however that Fx 3.5 depends on Fx 2.0 SP1 and Fx 3.0 SP1, which will ship at the same time.

3. VS2008 has a new simple yet powerful feature: multitargeting. The ability to create projects targeting different .NET Framework versions (2.0, 3.0 and 3.5). This means that even though VS2008 can be installed side by side with VS2005, you do not need VS2005 any longer since VS2008 offers a superset of the functionality.

4. There are many new C# 3.0 and VB9 language features (inc. automatic properties, relaxed delegates, object initialisers, type inference, anonymous types, extension methods, lambdas and partial methods). The compilers emit backward compatible IL, which is to be expected since there is no new version of the CLR. In plain terms this means that all the new language features can be used with existing v2.0 projects (due to the multitargeting feature mentioned above)! VB developers also get enhanced intellisense amongst other IDE features.

5. The headline feature of this release is LINQ (Language Integrated Query). LINQ depends largely on the language features that were introduced and also on bits of the Fx 3.5 (4 assemblies to be precise). LINQ is a new declarative paradigm for querying data sources in a consistent manner, regardless of what the data source is: in memory objects, XML, SQL, DataSet or anything else (because LINQ has been architected to be fully extensible). The future looks even brighter with efforts such as PLINQ.

6. For the web developer, ASP.NET AJAX ships out of the box with improvements and ASP.NET 3.5 includes 3 new controls. There are also enhancements in the IDE that can be used in ASP.NET 2.0 projects too, such as support for JavaScript intellisense and debugging, a new CSS engine and an HTML designer that supports Nested Master Pages.

7. For the client developer, new features include WPF project templates out of the box, a new WPF designer with integrated support for interop between WinForms and WPF. FireFox support for ClickOnce and XBAP deployments. Now, you can take advantage of ASP.NET provider services and also embed UAC manifests for application running on Windows Vista.

8. For the office developer, there is full support for 2007 Office customisations as well as Office 2003 templates. Support include outlook form regions, ribbon customisation, custom task panes, actions pane, Word content control databinding and interop with VBA.

9. For the server developer, WCF and WF templates now ship out of the box and play better together. WCF now supports a SOAP-less HTTP programming model as well as syndication and JSON serialization. There is a good collection of links for these here.

10. For the mobile developer, there are tons of new features including support for Compact LINQ and Compact WCF and many other NETCF features. At the IDE level we get Unit Testing for devices amongst other goodies from the VSD team.

11. Bonus item: It is only via VS2008 that you will be able to debug your code down into the .NET Framework methods.