Silverlight 2 is finally released!
If you plan using it you need to install three things:
The nice thing is, Silverlight Tools not only work in VS 2008, but also in the free version Visual Web Developer Express. Therefore you can develop Silverlight apps for free.
The Silverlight Tools contain everything you need:
There is also a Eclipse Tool for developing Silverlight applications. This tools is being developed by Soyatec in cooperation with Microsoft.
If you have used Silverlight before, see the Breaking Changes Document for new features of Silverlight RTM, which break the pre-release API of Beta 2.
That's a good point: Update your Silverlight Beta apps to RTW as soon as you can. They cannot be viewed with the new runtime!