Yes, it's true. The final, RTM version of the .NET Framework 3.0 and associated SDK were released today. And there was much rejoicing!
- .NET Framework 3.0 Runtime - note that you do not need to install this if you're running Windows Vista, because it's installed by default. You will, however, need to install it on the other supported platforms like Windows XP and Windows Server 2003. As you might guess, the runtime allows you to run .NET Framework 3.0 applications. Check out the readme for more details.
- Windows SDK for Windows Vista and .NET Framework 3.0 - if you'll be building .NET Framework 3.0 applications, this is the software development kit that provides documentation, tools, samples, etc. Check out the Windows SDK Release Notes for more.
- Visual Studio 2005 Extensions for .NET Framework 3.0 (Windows Workflow Foundation) - this provides Visual Studio 2005 support for building Windows Workflow Foundation applications. If you're not building Windows Workflow Foundation applications, you don't need to install this. This one has Release Notes too.
- Visual Studio 2005 Extensions for .NET Framework 3.0 (WCF & WPF), November 2006 CTP - adds features to Visual Studio 2005 for building Windows Communication Foundation (WCF) and Windows Presentation Foundation (WPF) applications: XAML Intellisense, project templates, and .NET Framework 3.0 SDK documentation integration. This also installs an early version of the visual designer for WPF applications, code name "Cider" (check out their Wiki).
If you have earlier versions of these packages installed on your machine, be sure to read and follow the uninstall instructions.