Yes some one has got OSX running on 'normal', non mac hardware. I did a post about this some time ago and to be honest I'm kind of surprised it's taken this long to do.
Maybe the reason is, as I speculated in the last post about this, that using a mac is a whole 'experience' and it's not just the software or the hardware but both. Oh dear, I've just used experience as some one from marketing would, sorry!
Or maybe it's that the fact that not a lot of hacking is actually needed, so it's not a big enough challenge for the hardcore hacker but it's still involved enough that only the dedicated are going to try it.
What ever the reason it was always going to happen after apple went to using intel chips.
So should apple worry at this point? No 99% of people that are going use macs are those people, like me, that love the apple experience and we are just not going to get that from a standard PC. Yes you could say I'm an apple sob (and proud of it!)
There will be a very few that will try this and use it regularly, but I would guess that most people will try this as a bit of an experiment and then go back to using OSX on their apple hardware.