In case you haven't noticed, the final release of Silverlight 2 went live last week! Silverlight 2 is Microsoft's next generation cross-platform, cross-browser web development platform. It enables rich experiences within the browser using .NET technologies. Silverlight 2 is a subset of the Windows Presentation Foundation (WPF) that runs in the browser and does not require the .NET Framework to be installed on your computer. The development environment is with Visual Studio 2008 and allows you to develop web applications using the same development and debugging tools as other managed code applications. If you haven't tried it out yet, I highly recommend it! Here's a link to Get Started Developing with Silverlight 2. There is also a Silverlight Showcase showing off some really cool Silverlight applications. Scott Guthrie has a nice blog post also that describes more details of Silverlight 2 if you are interested.
Note: if you have Silverlight 2 Beta 2 installed, you will need to uninstall it first before installing Silverlight 2.