Apple announced yesterday at their event that the newest version of OS X, version 10.9 (Mavericks), will be free to all Macintosh computers that can run it. This is pretty amazing, we can finally keep all of our Macs on the same OS instead of us currently supporting three different versions.
But for hackintosh users, it means that there is no longer a way to purchase a legal copy of OS X. A hackintosh is a computer that is assembled out of parts that can be made to run OS X. It's a way to get a Mac without paying for a Mac. A lot of users of hackintosh like the challenge, like OS X, but for the most part Apple doesn't offer a hardware configuration for them. That ends now for those that try to stay as legal as possible, although a hackintosh was never quite legal. The OS X terms of service require OS X to be used on Apple labeled computers, which means even if you buy a copy it's still not quite legal.
Although this is probably not what Apple had in mind, it is the end of an era.