I've been spending time discovering the capabilities of the Windows Workflow Foundation in the .Net 3.0 framework. This by far the most flexible workflow framework I've seen in a long time. Most of the articles on the web tout the Windows Presentation Foundation or Windows Communications Foundation features with very few workflow articles.
What makes this a powerful solution is the plugin nature of the workflow services as well as the ability to model activities in a domain specific fashion. Let's face workflow's are all around us and for the most part these are modeled in code that is fragile or by complex and expensive solutions.
So what do you need to start developing workflows today? You'll need to install the .Net 3.0 runtime as well as the Windows Vista platform SDK. In addition if your using Visual Studio 2005 you can install the Visual Studio Extensions for Windows Workflow Foundation.
If your development includes workflows, you owe it to yourself and your team to look at the Windows Workflow Foundation as solution to solving your workflow issues.