Since before JavaOne in June, I've both asked and heard the question, "What can be done with an open source Java that cannot be done today?" Now, it seems that this question has been publicly asked, as Onno Kluyt, chairman of the Java Community Process, has just done in a recent article at MacWorld UK.
To be very honest, I think this question is now a bit outdated. Now that the JCP rules allow for an open source implementation of Java, it is clear that we will have an open source implementation, no matter what Sun thinks about it. So we should start asking the next question: "What will Sun (and all the rest of us) do to have a complete and compatible open source implementation?"