This is old news, but Brain Groth and Mark Berman released a demonstration of what I'll call a true-blue SOA hosted on Channel9. Very impressive piece of demo encompassing many applications and technologies. We see
1. Webservices built on top of legacy systems
2. BizTalk and webservices working it's magic
3. Integrations with AS400s, SAP and some other systems
4. SQL Server, Unix, J2EE Websphere, Speech Server and many systems which are unlikely to work together.
5. Business processes driving systems instead of systems driving the process, which should be the case.
Go check the 17 minutes demo when you got the time. Great stuff!