.Net Framework 3.0 Vs 3.5 Vs 4.0 (.Net FrameWork Comparisions)

NET Framework 3.0 consists of four major new components:

• Windows Presentation Foundation (WPF), formerly code-named Avalon; a new user interface subsystem and API based on XML and vector graphics, which uses 3D computer graphics hardware and Direct3D technologies. See WPF SDK for developer articles and documentation on WPF.
• Windows Communication Foundation (WCF), formerly code-named Indigo; a service-oriented messaging system which allows programs to interoperate locally or remotely similar to web services.
• Windows Workflow Foundation (WF) allows for building of task automation and integrated transactions using workflows.
• Windows CardSpace, formerly code-named InfoCard; a software component which securely stores a person's digital identities and provides a unified interface for choosing the identity for a particular transaction, such as logging in to a website.

Changes in 3.5 since 3.0

• New language features in C# 3.0 and VB.NET 9.0 compiler
• Adds support for expression trees and lambda methods
• Extension methods
• Expression trees to represent high-level source code at runtime.
• Anonymous types with static type inference
• Language Integrated Query (LINQ) along with its various providers
• LINQ to Objects
• LINQ to XML
• LINQ to SQL
• Paging support for ADO.NET
• ADO.NET synchronization API to synchronize local caches and server side datastores
• Asynchronous network I/O API.
• Peer-to-peer networking stack, including a managed PNRP resolver
• Managed wrappers for Windows Management Instrumentation and Active Directory APIs
• Enhanced WCF and WF runtimes, which let WCF work with POX and JSON data, and also expose WF workflows as WCF services. WCF services can be made stateful using the WF persistence model.
• Support for HTTP pipelining and syndication feeds.
• ASP.NET AJAX is included.

Key focuses for 4.0  release are:

• Parallel Extensions to improve support for parallel computing, which target multi-core or distributed systems. To this end, technologies like PLINQ (Parallel LINQ), a parallel implementation of the LINQ engine, and Task Parallel Library, which exposes parallel constructs via method calls., are included.
• New Visual Basic .NET and C# language features, such as statement lambdas, implicit line continuations, dynamic dispatch, named parameters, and optional parameters.
• Support for Code Contracts.
• Inclusion of new types to work with arbitrary-precision arithmetic (System.Numerics.BigInteger) and complex numbers (System.Numerics.Complex).

Source: wikipedia.org