According to, Apple has purchased the company behind CUPS and the Copyright of CUPS source code. Apparently this does not affect licensing of the current version of CUPS, still under GPL2/LGPL2, but I wouldn't be that optimist about the future. Note that in the past Apple had already paid a premium for a license exception that allowed them to evade the GPL2, and even though they published their modification to CUPS itself, they never released the whole stack as they would have if it at been GPL2.

Time will tell... but I'd recommend starting to mirror everything just in case Apple pull the plugs.

Note: this is a pessimist view. But it just remind why at one point copyright assignment might not be good.