I know WWF is still in Beta form but it seems stable enough

We would love for you to start using Windows Workflow Foundation right away. It is currently available as Beta 1 with Beta 2 planned for December 2005 and RTM in H2 2006. You can begin development with the technology now though you should expect some additional time and risk due to the unreleased nature of it right now. And ideally you would do this with a project that is planned for release to production after our release date. There are also two main downsides to working with Beta software which you should consider.

1) Our End User License Agreement (EULA) for the Beta of Windows Workflow Foundation does not allow you to use it in a production environment. We don't want customers to have bad experiences with Microsoft software and we are really focussed right now on releasing the best final product possible.

2) You cannot get formal support from Microsoft for unreleased software. That means if you go ahead, you can ask questions on this MSDN Forum - but there isn't a guarantee that you will get an answer. And you can't call Microsoft support and ask them for help either.

There are early adopter programs that Microsoft customers can apply for which can help with the above issues. These programs benefit customers with early access and they benefit Microsoft with product feedback and validation. To get involved with these you should contact your regular Microsoft Account Rep and ask to about these programs which are delivered through the Microsoft DPE group.

To your comment about BizTalk Server. BizTalk Server is available now and it's an enterprise server product which also includes BAM features, B2B features, numerous application adapters for EAI, business analyst toolks and a scalable-deployable-monitorable-maintainable server. BizTalk Server is also a part of Microsoft's workflow strategy long term as a premium server product. If you want to build a workflow solution on BizTalk Server now, there will be support for migrating to Windows Workflow Foundation in the future. Windows Workflow Foundation is also part of that strategy in the developer platform and provides for folks to build their own client or server applications involving human / system workflow and rules engines.