Confused about what .NET 3.0 is and is not, and what the next set of libraries after 2.0 will be called? Here's a pretty comprehensive summary from Julie Lerman that lays it out for you.
.NET 3.0 is.NET 2.0 plus the four new components [WPF, Cardspace, WCF, Workflow]. Those four core technologies are called the ".NET 3.0 Components".
The four new components were developed as part of the Vista effort but are so cool that everybody wanted them to be available downlevel, which they are to varying degrees. Julie also gets into Orcas, Atlas/Ajax, LINQ, and what works with what and when (roughly) you'll see it. Check it out.