This blog post summarizes the new features of ASP.Net 3.5 and VS 2008 IDE.
Below are the new features been introduced.
Before we go further let’s have a quick view.
Compatibility - From VS 2005 to VS 2008 and .NET Framework 2.0 to 3.5?
Though .NET Framework 3.5 is a super compatible upgrade from .NET 2.0, it does not require you to change any code in order to target the new framework version. Only non-breaking modifications to existing .NET assemblies have been made in the .NET 3.5 release, and wherever possible added new features in separate assemblies to minimize the chance of breaking changes.
Also no project model or build changes have been made with VS 2008. Both the "web site" and "web application project" models will be fully supported going forward.
Nested Master Page Support
Here I have been putting major points only. For other details, how it works please folow the below link.
ASP.NET 2.0 supports "Nested Master Pages" - where you can create a root master page for a site that defines a site's overall layout, and then create nested master pages that are based on the root master and further customize the layout. However the problem is pages based on Nested Masters can't be edited within the VS 2005 WYSIWYG designer.
Nothing to add more.
Hope this helps.
Thanks & Regards,
Arun Manglick || Tech Lead