Have you seen the new Times Reader? This is a beta product from the NY Times that will knock your socks off; it shows what can be done with .NET 3 and it is beautiful (not to mention free).
When .NET 2 arrived there was no push from users to move from existing technology to the new .NET technology, and adoption was slow. Add to the lack of perceived benefit by those paying the bill, the outright resistance from traditional VB programmers (VB.NOT) and Microsoft had an uphill battle.
My prediction is that once Microsoft rolls out Vista and .NET 3 and Orcas (Visual Studio next) , and once new products start to hit with the new look and feel, clients are going to start to demand that their new products have the nifty new look and feel, the better fonts, the cooler features, etc. etc. that you can only achieve with WPF. Add to that the ability to create contract-based web services, integrated work flow for a far more sophisticated business layer and (not coincidentally) the best Ajax library available, and .NET 3 (broadly defined) will, I suspect, see a far faster uptake (read 2-3 years instead of 5-6) than .NET 2.
For a first look at why, see the Times Reader.