Features of Silverlight 5

Improved media support

• Low Latency Audio Playback: Use the SoundEffect API to trigger low-latency sound
• Variable Speed Playback: allows video to be played at different speeds and supports fast-forward and rewind. At up to twice the speed, audio pitch correction allows users to watch videos while preserving a normal audio pitch.
• H/W Decode of H.264 media: Significant performance improvements with H.264 media decoding of unprotected content
• DRM Key Rotation/LiveTV Playback: Long-running live TV playback is protected through the use of rotating licenses
• Application-Restricted Media: Prevents playback of protected content in unauthorized applications

Improved Text support

• Text Tracking & Leading: Exercise fine-grained control over the spacing between characters and lines in your text
• Linked Text Containers: Create linked RichTextBlocks that allow text to flow seamlessly from one to the next
• OpenType and Pixel Snapped Text : Improved text clarity
• Postscript vector printing: reduces the size of print jobs and improves rendering quality of text
• Performance improvements for Block Layout Engine.

Building next-generation business applications

• PivotViewer -- now included in SDK. Adds support for dynamic client-based collections, XAML-based visuals, and customizability.
• ClickCount: Add support for multi-click to your application
• Listbox/ComboBox type-ahead text searching: Listboxes and ComboBoxes can now scroll based on text input
• Ancestor RelativeSource Binding: Bind to a property on a parent control
• Implicit DataTemplates: Allow DataTemplates to be defined implicitly
• DataContextChanged event
• Added PropertyChanged to the UpdateSourceTrigger enum
• Save File and Open File Dialog: Specify a default filename when you launch your SaveFileDialog and specify a default directory when you launch your OpenFileDialog
• Databinding Debugging: Set a breakpoint directly in XAML, examine locals, and debug your bindings
• Custom Markup Extensions: Execute custom code at XAML parse time
• Binding on Style Setters: You can now specify a binding within a style

Silverlight 5 performance improvements

• Parser Performance Improvements: Improved XAML parse times for UserControls & ResourceDictionaries
• Network Latency Improvements: Significant performance improvement in ClientHttpWebRequest scenarios
• H/W accelerated rendering in IE9 windowless mode: Silverlight now uses the new SurfacePresenter APIs for H/W accelerated rendering in IE9 windowless mode
• Multicore JIT: Shortens the start-up time for Silverlight apps
• 64-bit browser support

Graphics improvements

• Improved Graphics stack: The graphics stack has been re-architected to add features such as Independent Animations
• 3D: Use the XNA API on the Windows platform to gain low-level access to the GPU and draw vertex shaders and low-level 3D primitives. Includes Render targets, XNA built-in effects, surface composition settings for depth/stencil buffers and multi-sample anti-aliasing

Silverlight 5 extends features of the "Trusted Application" model

Silverlight 5 extends features of the 'Trusted Application' model to the browser for the first time. These features, when enabled via a group policy registry key and an application certificate, users won't need to leave the browser to perform complex tasks:

• Multiple window support: Launch multiple top-level windows inside a SL OOB application
• Full-Trust in-browser: Using Group Policy, deploy signed in-browser applications that harness the full power of full-trust functionality
• In-browser HTML support: Host your WebOC within an in-browser SL application
• Unrestricted File System Access: Read from and write to any directory on your system, from a full-trust application
• P/Invoke support : Allows existing native code to be run directly from Silverlight

Tools improvements

• Visual Studio Team Test support.