Alan Cooper and Kent Beck debate XP vs Interaction Design. Alan Coopers' book The Inmates are Running The Asylum describes Interaction design.
Not sure what 'interaction Design' is, but from the article it appears to be some type of business analysis that occurs prior to software development. The assumption is that users need 'help' in deciding what it is they want built. Rather than just automating what is, we should be designing something better. Sounds similar to the Business Process Re-engineering ideas of the late Nineties.
In my post on software as art, I point out that there isn't much guidance available on how best to envision new software systems. I'm not sure whether having a middle man between customers and developers is the right idea though.
It is all well and good, if your Interaction Designers are good at what they do and add value, but how do you test this? Also how do you keep the customer accountable for how he chooses to spends his money?
All sounds a bit naive to me.
Envisioning should be a customer/marketing responsibility, with developer input on feasibility and cost.
I'm with Kent Beck on this one.