Dear WD,
So the problem with Black is that it requires specific drivers/software to make it cache as it should? In that case I can’t see it ever working on a PS4, or am I wrong?
Shame really, always been very happy with my WD-drives! You probably should look in to it right now people are already complaining about that a 500gb 5400rpm is not what they think is ideal for PS4, don’t even know about the XBO!
Would probably have sold quite a few, in Sweden its about half the price compared to a 1TB SSD, which makes it very attractive option, the other hybrid drives on the market here just have 8gb of ssd which wont be sufficient for a PS4, whilst 120gb sold have been well enough.
You can’t see past a market that sold 1 000 000 in it s first 24h, only in the US: 
As you can see, 4 days after the release here (11/29/2013) there are already quite a few upgrade kits avaiiable. http://www.webhallen.com/se-sv/sok/?Change=1&Text=ps4+upgrade&SectionId=
Pardon that some of the text is in swedish, but the rellevant info is there!
So my question is really, will it work att all and in that case WHEN? 
Kind regards,
Niklas Rundgren