Dragos and Boris have a new draft of their Orchestration Patterns book. There is a discussion list as well. One thing I am on the lookout for was mentioned in an ealier post today... Ralph Johnson's point about structure *and* process. Beyond the question of what is an "orchestration" vs. some other kind of programming... what is the process for adopting one when it is called for.
One thing I like about orchestration tools is support for increasingly transparent reliability across long-running, asynchronous operations. I don't see how this would ever become completely transparent, but on the one hand most programming languages offer nothing by default, while orchestration tools try to offer something by default.
Other than that the current tools I am familiar with leave much to be desired in terms of programmer comfort... at least this programmer is not fond of "programming via property boxes". Perhaps we need something like Rails, but rather more for long-running, asynchronous process steps.