I have been doing a lot of work with Indigo and Service Orientation recently. I've been keeping quiet partly because Indigo was just about to have its big party, but mostly just because I've been busy.
Like any programming language or development style, I like to think of a service oriented style as a combination of conceptual models (what), implementation details (how), and tooling (assistance).
We are some way down the road to having solid options for all three, but one of the more interesting discussions to follow right now is in the conceptual space.
Steve Maine has made an excellent post about conceptual models and the interplay between the conceptual models and implementation. Its so good that even Don Box linked to it.
And if that kind of thing interests you, Steve has a bunch of links in his post that will give you hours of reading material :)