At one place I’ve worked, we sort of had a version of this. They called it “design immersion”. It was our big Far East clients that sometimes had an internal design team, they would send one or two of their staff to us in order for them to learn and experience Western culture/ways of working.
They’d work on all of our projects and then be able to also work on the project for their respective company to see how we would tackle it. Was a great experience from both sides and obviously good for building a long lasting relationship between client and consultancy.
I agree though it would be cool to work somewhere that does something completely different to your current employer and be able to tap in to the knowledge of the people at the other place. So really, how does this happen?