These are important for two very different reasons.
Firstly, although WS-Addressing has progressed to a Candidate Recommendation, in order for it to become a W3C standard, we had to demonstrate to the Directors that it was interoperable. This required a minimum of 4 implementations showing interoperability of all mandatory features of the specification, as well as two implementations that demonstrated interoperability of optional features. If the requisite number of implementations hadn't been available, or they had not been able to show interoperability, then the specification would have stalled. This would have been an extremely bad thing for the Web Services arena in general, and in particular the working group, where we've been working for well over a year so far. The testing group spent a lot of time and effort on this, and it all came together in the end. Although JBoss wasn't able to participate in the January 2006 interoperability event we made a concerted effort to help this time round and along with everyone else it helped.
Secondly WCF is an important technology from Microsoft, but also for Web Services in general: like it or not, a lot of Web Services applications will be built on this technology, so it is important for JBoss to ensure that we can interoperate with it for our customers and partners. The Plug-fest tested a lot more than just WS-Addressing, covering a range of specifications from basic SOAP all the way through to transactions, which we've demonstrated interoperability of in the past. There was a good attendance at the event and we certainly held our own with the likes of Microsoft and Sun.
What I hope this demonstrates is that we are fully committed to open, interoperable standards and will do all we can to ensure they are a reality. Interoperability events such as these are also an important part of our development process and you should expect to see us attending them on a regular basis, other commitments permitting.