[Source] ZBrush Central
Pixologic has announced ZBrush 4R2b and is planned to be released in the second half of December 2011 as a free upgrade to all registered users.
Now that Z4R2 has been put to the test by ZBrush users, on many different system configurations and workflow, Pixologic found some ‘rough corners’ which needs polishing. Therefore, Pixologic will be releasing an update patch allowing you to take full advantage of the powerful features in Z4R2 as soon as possible, without having to wait until Z5 is released. A few extra goodies may also be included with the next update.