Microsoft Silverlight is a powerful tool for creating and delivering rich Internet applications and media experiences on the web. Silverlight 5 builds on the foundation of Silverlight 4 for building business applications and premium media experiences. Among other capabilities, the Silverlight 5 release candidate highlights dramatic video quality and performance improvements, and features that improve developer productivity.

The final Silverlight 5 release will be available in 2011. The following article is referenced from http://www.microsoft.com/silverlight/future/

Improved media support and rich UI capabilities

- Hardware Decode and presentation of H.264 improve performance for lower-power devices to render high-definition video using GPU support.
- TrickPlay 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.
- Improved power awareness prevents the screen saver from being shown while watching video and allows the computer to sleep when video is not active.
- Remote-control support allows users to control media playback.
- Digital rights management advancements allow seamless switching between DRM media sources.  

Building next-generation business applications

Silverlight 5 text (bottom) has improved clarity.
Fluid user interface enables smoother animation within the UI. Inter-Layout Transitions allow developers to specify animations to apply when elements are added, removed or re-ordered within a layout. This provides smoother user experiences when, for example, items are inserted into a list.

Text improvements make it possible to build rich magazine-style text layouts:

- Multicolumn text and linked text container allow text to flow around other elements.
- Tracking/leading set precisely how far apart each character is for full creative control.
- Text clarity is improved with Pixel Snapping.
- Text layout performance is significantly improved.
- OpenType support has been enhanced.

Printing:

- Support for Postscript vector printing enables users to create faster, higher-quality reports and documents, including the ability to create a virtual print view different from what is shown on the screen.

Controls:

- Added support for double-click and Combobox type ahead.

Model View ViewModel (MVVM) and Databinding enhancements allow more work to be done more easily via XAML:

- Debugging support now allows breakpoints to be set on a binding, so you can step through binding failures.
- Implicit DataTemplates allow templates to be created across an application to support a particular type by default.
- Ancestor RelativeSource allows, for example, a DataTemplate to bind to a property on the control that contains it.
- Binding in style setters allows bindings to be used within styles to reference other properties.
- The DataContextChanged event is being introduced. Markup extensions allow code to be run at XAML parse time for both properties and event handlers, enabling cutting-edge MVVM support.
- UpdateSourceTrigger allows immediate response to data entry, leveraging ViewModel functionality through databinding.
- Multiple Window support, enabling user to multi-task various functions within a common application.
- CustomTypeProvider, enabling post deployment configuration of product catalogs and other object definitions.
- CustomMarkupExtensions enabling better tooling and code optimization by extending XAML definitions to custom code.  

Silverlight 5 performance improvements

- Reduced network latency by using a background thread for networking.
- XAML parser improvements that speed up startup and runtime performance.
- Support for 64-bit operating systems.
- Reduced network latency by using a background thread for networking.
 
Graphics improvements

- Graphics Processing Unit (GPU) accelerated 3-D application programming interface (API) provides rich graphics on the Web for building advanced data visualizations and rich user experience (UI).
- Immediate mode graphics API allows direct rendering to the GPU.
- Hardware acceleration is enabled in windowless mode with Internet Explorer 9.

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, mean users won’t need to leave the browser to perform complex tasks:

- Host HTML content as a web browser control within the Silverlight application. HTML pages, such as help content or e-mail, can be integrated within the application.
- Read and write files to the user’s My Documents folder, making it easier to find media files or create local copies of reports.
- Launch Microsoft Office and other desktop programs. Users can open Microsoft Outlook and create an e-mail message, or send a report to Microsoft Word utilizing the power of Microsoft Office.
- Access devices and other system capabilities by calling into application COM components. Users can access a USB security card reader or a bar-code scanner.
- Enjoy full keyboard support in full screen, which enables richer kiosk and media viewing applications. - - Call existing unmanaged code directly from within Silverlight with PInvoke.

Tools improvements

- Microsoft Visual Studio profiling support including CPU, memory, and thread contention