Hi guys, and thanks for the comments.
The tree-like objects’ texture/materials were done in a sort of two step process. After first modeling the main shape and giving a fair amount of detail with projection master, I apply a wood like texture (at high resolution using a high-rez texture image). I use the texture for masking the object and then add details with the inflat brush. Finally, the materials used are procedural quad shaders.
In fact, I learned a lot about using materials (and making zsphere trees) in froyd’s forum post on natural wood (http://www.zbrushcentral.com/zbc/showthread.php?t=23394). If you’re interested, he even lets you download the materials and the scene with the tree.
I’m currently drawing out ideas for my next creation, so more to come later.
cheers!