Fortune magazine has an interview with Bill Joy where Joy talks about his life after Sun. On the first page of the interview, he talks about building

a Net that is a lot less prone to viruses and spam, and not just by putting in filters and setting up caches to test things before they get into your computer. That doesn't really solve anything. We need an evolutionary step of some sort, or we need to look at the problem in a different way.

He then goes on to talk about writing everything in Java (C# would be fine by me too). He also talked about building software diversity by writing different implementations of the same module and running various combinations of modules as a way of obtaining diversity. These are interesting ideas. On page 2 of the interview his says:

People still don't recognize the scope of what we have to do. You can't simply write a new, multimillion-line program in C and expect it to be reliable unless you're willing to work on it for 20 years. It takes such a long time because that language doesn't support the easy detection of the kinds of flaws most viruses exploit to bring down systems. Instead, you need to use a programming language with solid rules so that you can have the software equivalent of chemistry: the predictable interaction of code as it runs. But on the network, where part of the software works here and part of it works there, programs also behave in emergent ways that are more biological and difficult to predict. So until you have a science of doing distributed computing, software developers will continue to just throw stuff out there. That's why the Net is not going to be secure.

This is why I'm looking for a managed platform.

On page three, he details his reasoning for leaving Sun.

Bill Gates faced a similar choice with his Longhorn project. He probably has a lot of great ideas and all these brilliant people, but he also has this antecedent condition he has to take into account-keeping it somewhat in sync with the old Windows. So the beautiful vision may fail because it has to be compatible. I've often wondered why they can't, for once, do something new. I mean really, really new? But then, when I asked myself that same question, that's when I knew I had to leave Sun.

I don't think he's trying to dig either Microsoft or Sun here. He's just saying that sometimes in order to do something really really new, you have to start over. But that only gets riskier as an industry matures, and every industry matrures a little bit each day. I hope that he will do something really, really new. I also hope that it will turn out to be something worth adopting.