Yes, this is definitely relevant to my interests as well. So far I haven't found anything as good as GC and even that is not as good as I would like it to be.
Besides gmail's superior spam filtering, this is the one thing I miss from google.
I look around once in awhile, and I never do find a good solution. My current solution is Thunderbird's Lightning extension, and I cringe every time Thunderbird updates, which is often now that Mozilla has the constant update fetish.
I would love to find a reasonably priced calendar solution with a company that I believe will be around for at least five years.
I really wish fastmail did calendars. Are you listening FM?