I'm familiar with the MIT license, but thanks. So if the copyrights to new code aren't important, why would Joyent seek to change that and want to "own" the code now?

I'm sure it makes it easier to market your services to the enterprise if you are the "official" owner of the project.

It also means they could offer a version under a license that is not MIT compatible, if they so desired.

But your FPL must be MIT compatible. Joyent does not have that restriction. They could sell a forked version that prohibits redistribution.

Where in the MIT license does it say you can't bar redistribution in your proprietary fork? That's obviously what everybody does when they use MIT code in their proprietary products? That's the whole point.

IANAL, but isn't that precisely what the MIT license requires? That everyone who gets a copy of the software must also have the right to modify and redistribute it for free?