nice post at http://blogs.msdn.com/sharepoint/archive/2007/05/14/understanding-the-sharepoint-calendar-and-how-to-export-it-to-ical-format.aspx
shame the is no conflict resolution
(via http://www.sharepointblogs.com/echef/archive/2007/11/07/sharepoint-connections-the-real-day-1.aspx)
"Many people know about the Calendar and Task 2-way syncronization with Outlook, but many people overlook the contact and discussion forum 2-way sync that also exists. The document lirary 1-way (read-only) view was supposed to be 2-way, but appearently there we issues around conflict resolution and the quality of this syncing that kept the 2-way version out of the release... Might be back on the table in the next version :)"