Windows Workflow Foundation has been officially announced at the PDC. Get a load of this, from Darren Jeffords blog;
For those of you familiar with BizTalk Server 2004, Windows Workflow Foundation is analogous to the Orchestration Designer and Orchestration Runtime (XLANG) in BizTalk. It allows you express your “workflow” using a designer and then have this executed by a runtime.
The Orchestration designer in BizTalk was fairly heavy-weight and not really suitable to be hosted and used in other applications (memory footprint, etc.), Windows Workflow Foundation is light-weight and re-hostable allowing you to integrate workflow functionality into your application.
I wonder what this means?
Business Rules are built into the designer allowing you to encode any flexible rules separate from the implementation allowing for easy modification.
WWF provides a framework for building and hosting workflows inside Windows apps. It will be part of the WinXF namespace along with Indigo and Avalon.
OK, no need to panic - from the horses mouth;
Future versions of BizTalk Server, MBS Applications and Office "12" will use this technology. As of today workflow is a new player in the middle tier for application development. Every application includes some workflow and with Windows Workflow Foundation you can capture that workflow in a model.