From a search on .bomb for "z fare EQM" I got the following:
"Plus, when you fly on United or United Express, Continental, US Airways, Air Canada and Lufthansa on a paid ticket in First Class (F A), Business Class (J* C D Z) and Unrestricted Economy (Y B), you can earn a 50% elite status miles / elite status segments bonus. So it's easier than ever to retain your Premier Executive status."
From my reading, it looks to be true if your are 2P, 1P or 1K. Not sure if it counts for GMs.
I have a Z fare on UA from FRA to ORD coming up. Hoping for 150% EQMs! I got 150% EQMs for BKK-ORD just a few weeks ago. That was a nice boost.