So here's the thing. I've not actually used Google calendar myself, so I thought I'd do some reading around and find out what some other folks have thought about it. As a sharing calendar tool the potential for this can be pretty good. I've come across some not great comments though, and for some the prospect of keeping another calendar up to date along with other calendars is not a great lure. At the moment I am one of those who thinks the benefits of this particular tool may not be huge for me personally at this particular point in time but I will be looking out for opportunities to use this.
In my previous role I think I could have made really good use of this, but I just don't do any collaborative work of this nature at the moment. Most of my colleagues don't even use outlook for anything other than an email service, let along any other web-based tools. I know some people outside of work use the mobile.me calendar if using Apple tools as it keeps things consistent.
Personally, I struggle to keep my personal calendar, my iPhone and my outlook up to date- my workplace uses outlook and they don't allow syncing with personal iPhones so I have to do this separately.