Open Calendar Solutions

[Dave Smith]

I am changing jobs soon, and I've come to rely on (shudder) my  
company's Microsoft Outlook/Exchange for my calendaring needs I store  
both personal and work-related calendar information there. I'd like to  
get rid of this closed solution once and for all and move to an  
alternative that meets the following requirements:

1. Easily synchronizable between applications (iCal, Windows Mobile  
Phone, iPhone, Google Calendar, etc)
2. Good longevity. I don't want to have to write magical shell scripts  
every 6 months because the format changed.
3. Can ingest my calendar data from Outlook.

What do you suggest?

Thanks!

--Dave