The folks from Pixologic continue to develop new useful tools. This latest one loosely resembles the old MetaReyes plugin, developed some years ago by Javier Reyes, from the Spanish company REM Infográfica. Check out the demo video at the ZBrushCentral. ZSpheres II will be part of ZBrush 3.5, which will be released as a free upgrade to all registered users (ZBrush 4 will be a free upgrade, too).