Sun trying again to kill Eclipse?
Sun pulled out of talks with Eclipse to cooperate because Eclipse don't want to kill themselves by handing over control to Sun.
Now Sun publishes an open letter saying that they don't want to abandon Netbeans in favour of Eclipse but that having 2 competing environments is a bad thing.
The only conclusion is that they're stating that the existence of Eclipse is "a bad thing"...

Nothing has changed.
I quote:
"Diversity -- with alignment -- will aid in creating a stronger Java community and industry. You've proved it. But don't define "interoperability" on your own terms, but rather work with other major players in the industry to achieve actual interoperability. Working with the Java Community Process[sm] (JCP[sm]) and the Java Tools Community (JTC) would be great entrees into the discussion. "

this is exactly what Sun has wanted Eclipse to do all along. Abandon their project to the JCP so Sun can stifle it completely (the average JCP proposal, if it makes it at all, takes several years which is far too long).

If they really wanted cooperation they'd have suggested a combined working group outside the JCP to maybe create a common plugin standard.
Such a group might work out, putting it inside the JCP is a carefully crafted recipe for failure.