Going from a proprietary system to open source, people still have to wait and see what will be open source - all of J2EE, the application server, the development tools or a more narrow part.

"I do not think anyone wants to break Java compatibility, but any of the large licensees with the market power to distribute their own version technically could do so, intentionally or unintentionally."

What exactly does Simon Phipps mean by this?

Sun executives don't live on the same planet as you and I do. They make up their own definitions as they go along. Here is a nice diagram of sun's strategy: http://origin.arstechnica.com/journals/microsoft.media/sunstrategy.gif.

I would love to have a Java I could tweak or compile for an iPaq, etc.

Open Source Java would speed adoption on a wider variety of "non-standard" platforms from a technical standpoint. This will make Java more ubiquitous (and probably better and more efficient as well). It will also satisfy the licencing zealots, having the same effect.