I had the great opportunity to participate on the ZBrush 4R8 Beta team for the past couple months! It's finally available to everyone, and if you've not upgraded yet, you should! The Live Booleans alone make it extremely useful!
Here is the Mechish Head I started with!
Check out all the other great artist's work from the official ZBrush 4R8 Beta Testing Gallery: http://www.zbrushcentral.com/showthread.php?207149-ZBrush-4R8-Beta-Testing-Gallery