This is an older story, but you may have missed it. (I did!) Insurance provider Safeco initiated a SOA effort and within that, built a new application using WebSphere Process Server, ASP.NET, and WCF Services written in C#. The story was written up on infoq back in May, but it is still very current. The business process flow was designed and run within the Websphere piece, the web front-end was ASP.NET, and many of the backend services were implemented in WCF.
Interesting question - WHY would anyone do this? The customer felt developing WCF Services was truly productive, and the ASP.NET web UI Framework was rich and high performance. On the other hand the customer liked the business process design tools available with Websphere Process Server.
Interesting - last I checked Websphere Process Server was $90,000/cpu (that's list price, mind you!), while running WCF Services on a Windows server will set you back around $4000/server. Yow! On a 2-way server (pretty typical), you're looking at $180,000 list price for software licenses. Ah but wait! There's more! Don't forget the software maintenance - you do want support don't you? That will set you back an additional 25% which is, oh, $45,000, per year! (The first year of maintenance is included in the $90k) The contrast in costs for infrastructure software is striking.
Zowie! you pay 10x more every year, just in Websphere maintenance, than you do for the one-time fee for a single Windows Server license necessary to run the WCF Services. Surely Websphere Process Server has a great deal of features that WCF lacks (such as a business process engine and a companion (extra cost) tool with a graphical designer for processes), but wow, that price differential is astounding. The closest comparable to Websphere Process Server in the Microsoft portfolio is BizTalk Server of course. BTS2006 includes a business process engine and a graphical designer for processes, much like Websphere Process Server. (and of course, unlike WCF) It includes a set of adapters to enable you to connect your business process to the other assets in your enterprise. It integrates nicely with WCF. The license cost for BTS2006 will run you about 1/4 the cost of the $90,000/cpu WebSphere license.
$omething to think about. . .