This newest snapshot of Moonlight 3.0 is nearly API complete with the upstream Silverlight 4.0 Beta, video capture support, SSE2 fast paths for gradient fills in the embedded Pixman/Cairo, Chrome/Chromium support fixes, element to element binding, a client HTTP stack, cascading styles are now supported, and there is a new right-click dialog.
Approaching API compatibility with Microsoft's Silverlight 4.0 specification is a step-forward and by the time the next Moonlight 3.0 release rolls around they expect to have 4.0 RTW compatibility. The SSE2 fast paths for gradient fills is also nice in that it should significantly improve performance for some operations. The video capture support is also another nice feature, but it's currently crippled in that right now it just works with YUYV and YV12/YUV420 pixel formats.
The release announcement for Moonlight 3.0 Preview 7 can be found on Miguel de Icaza's blog. The preview release can be fetched from the Mono/Moonlight pre-release site.