Theres a few MG books that have a page or two on the Zeds buts theres also a lot that stop at the MGB or (even worse) jump straight from the B to the F&TF with no mention of the Metro, Maestro & Montego - you can be sure there will be some coming up (curiously probably printed in China) that will show how great the Chinese MGs are with no mention of the Zeds at all.
Well we all love our ZS for one reason or another, but it is never going to be an iconic MG. Time will tell and I am sure it'll become a future classic purely for what fun it can give for little outlay. I truly believe the ZS180 was held back and could have been so much better had they had the balls to add a few more tricks to the package and made it a thoroughbred MG and not just a mildly tuned mid-range car.