I'm having a hard time writing up a complete answer, and will probably someday write an actual article, but I think the key for me is loose coupling of functionality and mobile code being a very interesting way to scale up a server farm. The whole thought of combining agents and tuple spaces into a system seems a lot closer to true reuse in software than objects has been. I think an agent programming language, a good speech act based communication language instead of the typical API, decent data types, and tuple spaces would make for a heck of a nice programming environment. I've had a hobby project for a long time to bring those elements together but I am still in the learning phase.