Bruno Souza, NetBeans community manager, has announced that Sun is considering releasing NetBeans 6.0 under GPLv2 with the Classpath exception, in addition to the current CDDL license.
A move like this would be well received by any of the NetBeans contributors, and will benefit the community at large.
Releasing NetBeans under the GPL license will also help align NetBeans with the Linux community and major open source projects. By making it easier to share NetBeans code and innovations with other projects, it will promote a stronger open source Java ecosystem.
The proposed dual license can be found here and a FAQ here. This change, which appears to be virtually a done deal, will bring NetBeans licensing in line with Sun's implementation of Java, which is also available under GPLv2. Sun can make such license changes because it holds the copyright on all the code (and requires any outside contributors to sign an agreement to that effect).
While this move will enable more open source code sharing, and is thus a Good Thing, it doesn't go far enough. It still shuts out sections of the open source community that use the Apache license or the very permissive BSD/MIT licenses. If Sun opened up Java and NetBeans under one of these licenses as well then it would pretty much eliminate any further question of license incompatibilities. Presumably Sun didn't want to go that far because it would allow projects like Harmony and Eclipse use the code.