MicrosoftProductsBuildingOnWindowsWorkflowFoundation. They would not choose a toy technology. These products include Microsoft Office SharePoint Server 2007, Microsoft BizTalk Server "vnext", Microsoft Speech Server 2007, Microsoft System Center "Service Desk", Microsoft Identity Integration Server "future version", and Microsoft Dynamics "future version".
It will be supported including the persistence service by regular Microsoft support once it releases in November 2007. Got a problem we can help!
WF has best practices like any programming model and following this guidance is important to be successful. Like any programming model If you try to work against the WF best practices you may hurt yourself. This wouldn't happen with a toy.
The APIs for WF are carefully factored and aligned with the rest of the .NET Framework so as to be familiar to .NET developers and extensible.
No development tool that uses CodeDom can be considered a Toy. For most people CodeDom isn't supposed to be fun.
Respected software architects (the scary smart kind) at Microsoft working on future internal applications are spending considerable time working on it
Performance is enterprise ready. We're publishing a performance whitepaper at release which will show the performance that can be achieved. You really want to think of WF as a set of services above managed code and perf is comparable to managed code. Check back on my blog for an annoucement of this in a few weeks.
Toys don't drive busines process like WF does. WF is being used by many many early adopters and we're going to publish snippets of this information on the community site in a couple of weeks time.
You can't buy WF at www.amazon.com/toys because it's free for installing on Windows XP, Windows Server 2003 and included with Windows Vista.