Hi all, bought Zb a few days back and have embarked on the learning curve using the Zclassroom stuff for newbies 
I hear and read very good things about this book, and was just wondering what version of Zb it refers to. It was release in June 2012 so I am assuming Z4r2 or r3.
There seems to be quite a change in Zb over recent months, particularly r4 - so I am keen to get the most relevant book and this seems to be it if it is up to date. Alternatively do you think I should wait for the fourth edition? Anybody have any news on that if indeed it is being worked by Mr Keller?
Thanks for any info.
Steve