I found this workshop very informative; I now have a much clearer grasp of how PHP allocates memory, and of the overall role of the Zend Memory Manager.
The only hiccup was with an attendee who brought a 32-bit system and could not install the 64-bit VM. However, Julien walked us through completing each exercise on the display, so I don't think anyone was unable to follow along and learn something.
This was a great talk overall with some good tips and real world examples. One nit-pick: I felt that some of the slides in the first half were a bit too busy and difficult to read (specifically the slides with Gherkin on the left and a list of bullets on the right). However, the rest of the slides (that just showed code) were much better.