Pat Helland is the newest member of my team to start a blog. Back in the day, Pat was a co-founder of the Microsoft Transaction Server team. These days, he's using the Metropolis analogy to help predict and explain the evolution of architecture. You can catch his Metropolis presentation as part of the Architecture Strategy Series). Subscribed plus I've added him to my teammate blog OPML file.
In addition to revealing his love of PEZ, Pat's got a great dissertation on the multiple meanings of the term "service". One of the issues with SOA is that not everyone agrees on what a "service" is. From what I can tell, the most common definition is "something you build with [insert your favorite vendor]'s technology". Having a vendor-independent description seems like a pretty good idea.