In his article Aaron talks about how interoperability requires teamwork, a good understanding of Web Services Profiles and also looks at some of the WS-I testing tools in action. Definitely a recommended read.
Reading this brings up a good point: Do you have what it takes to write for MSDN? Do you have an article (or even an idea for an article) that you would like to see live on the MSDN Web Services Interoperability page? Would you like to share your ideas and thoughts with thousands of readers?
If the answer to these is yes, click on the "contact" link to the left and drop me a note!