is it possible to do this in ZBrush?:
http://www.youtube.com/watch?v=iwgGAcd02PI&mode=related&search=
(not ZSpheres, but this sort of metamuscles thing)
look very intresting but no
Zspheres come close but ya that would be ALOT of subtools. It would be a very messy road. Not saying its not possible all the way but trust me you dont want to go down that path. "Things dont stay dead and dont come back right "(pet cemetary) 
Looks like a intresting program
also looks like he or she is sculpting about 1% and the other half is digging through menus
cant you accomplish something very similar with zspheres and unified skins?.. for instance, like this guy does
http://www.zbrushcentral.com/zbc/showthread.php?t=50581&highlight=zsphere
and without all the menu digging and stuttured workflow… that program looked interesting, but I think it still has a long way to go
Yeah, its definitively similar to zspheres.
I wouldn’t use this feature in 2.0 but now with the retopology, it might be very usefull to do muscular creatures…
Here’s an exemple, I think it would work much better on a body, but it shows he possibilitys…
For my opinion, just as its shown in the video, for zspheres sculpting, its better to keep the structure as simple as possible…
tutorial:
http://www.yoshii.com/zbrush/tutrial/tutorial01/Unified%20Skinning%20Tutorial.htm