I have a friend who would like to sink his teeth into a Lumia 920, but badly needs to use his Google shared calendars for work. He also has a massive amount of contacts and things, but as far as I'm aware, using the ActiveSync sign up (http://www.windowscentral.com/severe-windows-phone-8-bug-rears-its-head-gmail-users) should make all that work flawlessly. Shared calendars, though, I believe, are not supported. If anyone can tip me off to a suitable client (app) which can fit this shared calendar niche, there would be at least one more iPhone convert in the world.