Just noticed David Berlind's blog on OpenOffice.org's copyright assignment policies. It gets a few things wrong...for instance the assertion that the SISSL grants copyright to Sun. In fact the thing that does that is the Joint Copyright Assignment, a separate document which must be signed and on file at Sun before a contribution can be accepted into the main OpenOffice.org source tree from outside of Sun.
The JCA is the "new, improved" agreement. OpenOffice.org actually started with the same copyright assignment form that the FSF uses, but since mostly OpenOffice.org engineering happens in Europe there was much concern in the community to deal with problems arising from the unilateral transfer of copyrights in the FSF's form. The JCA was drafted by our friend Cliff Allen, a member of the Sun Legal Team and I did the proof-reading myself. At the time it was drafted the OpenOffice.org community was very happy to have an agreement that didn't ask them to do things they couldn't legally do (such as transfer their "moral rights", a concept that isn't handled too well in the FSF form).
The article makes it sound as if Sun is doing something exotic with the JCA in OpenOffice.org, but in fact all the FSF projects, all Apache projects, and many other open source projects ask for similar rights. The Apache folks will point out that they only ask for a license to relicense, but its essentially for the same reasons. Why? Well, in the US in order to use copyright law to "defend" a codebase you have to be able to represent a majority (51%) of the copyright holders. Imagine trying to assemble 51% of the hundreds of people who have signed a JCA for OpenOffice.org in a courtroom! Also, having the JCA allows Sun to maintain the dual-licensing (so if you donate code back under SISSL, Sun can also publish it under LGPL).
Licensing stuff is complex and hard to explain in sound-byte format, unfortunately...so its not surprising that David didn't get it exactly right. But he does have a point about the ability to respond to things like relicensing needs. I'm sure my pal Larry Rosen will want to chime in here, because he disagrees with the whole copyright aggregation idea. But Mozilla.org doesn't aggregate copyrights, and it took them a long time to track down enough of the contributors to get them to agree to add the LGPL to their license portfolio. No big company is going to unilaterally relicense. They'd risk a fork if they did. But the ability to build consensus within a community of current contributors without having to track down every contributor ever (even the dead ones) is compelling.