I dread asking this question but i feel like i must have missed
some delay. The last i heard, Zbrush4 was supposed to be
coming out in December but i haven’t even seen anyone ask
about it. Can someone fill me in with whats going on?
The 3.5 announcement tended to indicating the 4.0 schedule (e.g. in 2009) was chucked."In order to continue refining GoZ and other ZBrush4 features, we have decided to postpone the release of ZBrush 4 and instead release an interim ZBrush 3.5 for Windows and Mac users. Version 3.5 will have all the features of ZBrush 3.2 – including GoZ – as well as additional refinements."
I’m guessing that before we’re fully on the road to 4.0, we’ll see 3.5 Mac and GoZ PC, but with Pixologic announcements, one needs a rather large pinch of salt about future developments. 
-K