The .NET Framework 3.0 has officially been released!  You can download the .NET Framework 3.0 components here:

• .NET Framework 3.0 Runtime Components
• Windows SDK for Vista and the .NET Framework 3.0 
• Visual Studio 2005 Extensions for .NET Framework 3.0 (Windows Workflow Foundation)
• Visual Studio 2005 Extensions for .NET Framework 3.0 (WCF & WPF), November 2006 CTP

Note, if you are using Windows Vista the .NET Framework 3.0 Runtime Components are installed by default.

The Readme for the released version of the .NET Framework 3.0 is available here.  If you have a previous CTP installed, please be sure to review the uninstall instructions.   If you have questions about installing the .NET Framework 3.0, please post your questions to the .NET Framework Setup Forum.

PS. You can find .NET Framework 2.0 here