Moonlight 4.0 Preview 1 includes all the Silverlight 3.0 API and a part of Silverlight 4.0 API. New features include: Out-of-Browser, GPU-accelerated graphics, 3D transformation, shaders, V4L2 video capture, H.264 and AAC, and better smooth streaming.

Moonlight has skipped version 3.0, jumping from 2.4 directly to 4.0. Currently a beta preview, Moonlight 4.0 lets users leverage the entire Silverlight 3.0 API and some portions of the Silverlight 4 API. It has also been enhanced to run both inside the browser - Firefox 3.0-4.x and Google Chrome – and outside the browser in a sandbox or full-trust mode with the mopen command.

Some of the new features available in Moonlight 4.0 Preview 1 are:

GPU-accelerated graphics; Gallium3D is used on systems without adequate hardware acceleration

All Silverlight 3D transformations are supported

Supports shaders such as pre-defined blur, drop shadow effects, and user-defined shaders

A new abstraction layer has been introduced, called PAL, preparing the way to port Moonlight easier to other platforms with a different operating system, windowing and messaging system, and hardware configuration

Supports V4L2 video capture with YUYV or YUV420 pixel format

Developer tools: FPS display, disable GPU use, track exposed regions or clipping rectangles, show textbox bounds, and others

New codecs from Microsoft Windows Media Pack: H.264 and AAC

Better smooth streaming

Some of the missing features are: Printing, Microphone, UDP sockets, Analytics. The lack of support for DRM content makes impossible the rendering of protected media content, such as movies from Netflix, although Moonlight could do it. Partially completed features: Elevated Trust, RichTextBox, Navigation, WebCam, ChildWindow. Miguel de Icaza, Mono project founder and Developer Platform VP at Novell, mentioned the intent to complete the Silverlight 4.0 API support, but he did not specify if that will come with the final release of Moonlight 4.0 or with a subsequent release.