Silverlight 4 新功能列表：
增强企业级应用开发功能 -
打印支持 
提供超过60中可自定义，可样式化的控件，其中提供了新控件RichTextBox；另外增强了Datagrid功能，允许对于列数据进行排序和改变区域尺寸，另外支持行复制和粘贴； 
发布WCF RIA Service，方便在n-tiers 应用中对于网络和数据库的存取； 
增强项目本地化功能，提供双向文本功能，支持30多种新语言切换； 
支持.Net CLR类库引用，对于Silverlight桌面项目不用再做另行编译； 
增强数据绑定功能，使数据分组，编辑以及字符格式化更加灵活，效率更高； 
VS2010全新的设计开发工具，包括全套编辑设计界面，拖拉数据绑定功能，自动绑定控件，数据源选择，全代码自动感应系统； 
增强多媒体影像功能 -
网络摄像和麦克录音功能，允许共享视频和语音； 
在不用请求服务器交互的情况下，进行录音或者录像； 
允许拖拉或者复制粘贴外部数据到应用中； 
桌面应用，支持右键菜单； 
对于长列表控件，增加鼠标滚动效果； 
支持Google Chrome Browser； 
性能大幅度优化，Silverlight 4比Silverlight 3运行要快200%； 
Deep Zoom功能强化，增加硬件加速，另外，支持大型dataset，动画效果更加流畅； 
多点触控支持； 
组播网络支持，支持互动性网络会议，以及网络教学功能； 
H.264媒体内容保护； 
多媒体数据流输出保护； 
强化客户端功能 -
允许读取客户本地文件，例如读取我的文档，我的音乐，我的图片，我的视频等本地目录； 
允许运行本地桌面应用，例如Office，发送报告到Word文档，发送Email等功能； 
COM操作； 
组策略功能； 
增强键盘支持和全屏支持； 
增强网络支持，允许在没有策略文件下支持跨域访问应用； 
需要了解更多Silverlight 4 Beta新功能，请访问： http://www.silverlight.net/getstarted/silverlight-4-beta/
On November 18, 2009, at the Professional Developer’s Conference in Los Angeles, Microsoft Corp. unveiled a Beta version Silverlight 4. This latest version delivers hundreds of features and controls that, when combined with the continued innovation in Microsoft’s world-class tools for designers and developers — Microsoft Visual Studio and Microsoft Expression Blend – present the leading edge in rapid, powerful application development. With printing support, rich reporting and charting, and integration with back-end systems and server products including Microsoft SharePoint, Silverlight is ready for business.
New Features for Application Developers
Comprehensive printing support enabling hardcopy reports and documents as well as a virtual print view, independent of screen content. 
A full set of forms controls with over 60 customizable, styleable components. New controls include RichTextbox with hyperlinks, images and editing and Masked textbox for complex field validation. Enhanced controls include DataGrid with sortable/resizeable columns and copy/paste rows. 
WCF RIA Services introduces enterprise class networking and data access for building n-tier applications including transactions, paging of data, WCF and HTTP enhancements. 
Localization enhancements with Bi-Directional text, Right-to-Left support and complex scripts such as Arabic, Hebrew and Thai and 30 new languages. 
The .NET Common Runtime (CLR) now enables the same compiled code to be run on the desktop and Silverlight without change. 
Enhanced databinding support increases flexibility and productivity through data grouping/editing and string formatting within bindings. 
Managed Extensibility Framework supports building large composite applications. 
Exclusive tooling support for Silverlight, new in Visual Studio 2010. Including a full editable design surface, drag & drop data-binding, automatically bound controls, datasource selection, integration with Expression Blend styling resources, Silverlight project support and full IntelliSense. 
Developer tools
Fully editable design surface for drawing out controls and layouts. 
Rich property grid and new editors for values 
Drag and drop support for databinding and automatically creating bound controls such as listbox, datagrid. New datasources window and picker. 
Easy to pick styles and resources to make a good looking application based on designer resources built in Expression Blend. 
Built in project support for Silverlight applications 
Editor with full intellisense for XAML and C# and VB languages. 
Empowering richer, more interactive experiences
Silverlight is already in use as a comprehensive platform for building rich experiences both for application and pure media scenarios including HD quality, interactive video through Smooth Streaming. Silverlight 4 introduces additional capabilities to enable creation of ever more rich, appealing high-performance interactive experiences and innovative media experiences:
Fluid interface enhancements advance application usability through animation effects. 
Webcam and microphone to allow sharing of video and audio for instance for chat or customer service applications. 
Audio and video local recording capabilities capture RAW video without requiring server interaction, enabling a wide range of end-user interaction and communication scenarios for example video conferencing. 
Bring data in to your application with features such as copy and paste or drag and drop. 
Long lists can now be scrolled effortlessly with the mouse wheel. 
Support conventional desktop interaction models through new features such as right-click context menu. 
Support for Google’s Chrome browser. 
Performance optimizations mean Silverlight 4 applications start quicker and run 200% faster than the equivalent Silverlight 3 application. 
Deep Zoom enhancements include hardware acceleration to support larger datasets and faster animation. 
Multi-touch support enables a range of gestures and touch interactions to be integrated into user experiences. 
Multicast networking, enabling Enterprises to lower the cost of streaming broadcast events such as company meetings and training, interoperating seamlessly with existing Windows Media Server streaming infrastructure. 
Content protection for H.264 media through Silverlight DRM powered by PlayReady. 
Output protection for audio/video streams allowing content owners or distributors to ensure protected content is only viewed through a secure video connection. 
Move beyond the browser
Silverlight 3 pioneered the delivery of a new class of Rich Internet Applications to work on the desktop without additional code or runtimes. Silverlight 4 extends this capability:
For Sandboxed applications
Place HTML within your application enabling much tighter integration with content from web servers such as email, help and reports. 
Provide support for ‘toast’ notification windows, allowing applications to communicate status or change information while the user is working on another application through a popup window on the taskbar. 
Offline DRM, extending the existing Silverlight DRM powered by PlayReady technology to work offline. Protected content can be delivered with an embedded license so that users can go offline immediately and start enjoying their content. 
Control over aspects of UI include window settings such as start position, size and chrome. 
For Trusted applications
Read and write files to the user’s MyDocuments, MyMusic, MyPictures and MyVideos folder (or equivalent for non-windows platforms) for example storage of media files and taking local copies of reports. 
Run other desktop programs such as Office, for example requesting Outlook to send an email, send a report to Word or data to Excel. 
COM automation enables access to devices and other system capabilities by calling into application components; for instance to access a USB security card reader. 
A new user interface for requesting application privileges access outside the standard Silverlight sandbox. 
Group policy objects allow organizations to tailor which applications may have elevated trust. 
Full keyboard support in fullscreen mode richer kiosk and media applications. 
Enhancements to networking allow cross-domain access without a security policy file. 
To learn more about these features, visit the PDC09 site to view sessions from the conference!
Below is more detailed information on where you can get the Beta and resources to help you get started learning.