* What's New in .NET 3.5

It is recommended to read first 'What's New in C# 3.0'

ASP.NET

• Support for enabling existing ASP.NET 2.0 pages for AJAX
• Creation of ASMX & WCF based web services and consuming them from AJAX Library
• ASP.NET server side application services like authentication, roles management exposed as web services
• ASP.NET Merge Tool - a new tool for merging pre-compiled assemblies
• New ListView control which supports edit, insert, delete, sorting & paging
• ASP.NET integrated with core IIS 7.0 which makes ASP.NET services like authentication & caching available for other content types also.
• Microsoft AJAX Library to support AJAX based web development

Base Classes & CLR

• Support for CSharp 3.0 including LINQ.
• HashSet : A high performance collection of type set.
• Time Zone Improvements : to develop applications which operate in multiple time zones
• Minor Improvements in Threading, Reflection and controlling the GC behavior

Others

• Client Application Services : All windows based application to use ASP.NET login, roles and profile services hosted on central server.
• Occasionally Connected Services (OCS) : keeps windows application's local and remote data in sync.
• 'Silver' : code name for a new technology which unifies WF and WCF
• WCF Syndication : WCF services exposing syndication feeds. Supports Atom 1.0 and RSS 2.0

Other Posts

• Jasper : On the fly data access using Entity Objects
• C# 3.0 New Features : All LINQ(K)ED in one
• What's New in CSharp 3.0
• LINQ : An Introduction
• ADO.NET : Past, Present & Future
• Windows Communication Foundation : A Primer - Part 1