According to Scott Guthrie over at ScottGu's blog, the final version of Silverlight 1.0 has been released. C# support is still only included in the Alpha 1.1 Refresh, so our tutorials will continue to use that runtime.
There's even better news for all the Linux users out there. Microsoft has partnered with Novell to officially provide support for a Linux version of the Silverlight runtime. The Linux version, called Moonlight, is being developed by the same group that brought the .NET framework to the Linux Desktop.