<p>What are some of the new features that can be used in .NET 2.0 that are specific to C# 3.0/3.5 after upgrading to Visual Studio 2008? Also, what are some of the features that aren't available?</p>

<p><strong>Available</strong></p>

<ul>
<li>Lambdas</li>
<li>Extension methods (by declaring an empty System.Runtime.CompilerServices.ExtensionAttribute)</li>
<li>Automatic properties</li>
<li>Object initializers</li>
<li>Collection Initializers</li>
<li>LINQ to Objects (by implementing IEnumerable extension methods, see <a href="http://www.albahari.com/nutshell/linqbridge.aspx" rel="nofollow noreferrer">LinqBridge</a>)</li>
</ul>

<p><strong>Not Available</strong></p>

<ul>
<li>Expression trees</li>
<li>WPF/Silverlight Libraries</li>
</ul>

Lambdas & Extension methods are handled purely by the compiler and can be used with the .Net 2.0 framework.