I haven't been able to figure out how to populate the Sharepoint calendar with the shared calendar from the Outlook 2007 accounts connected to Sharepoint. Is this possible, or does the Sharepoint calendar have to be separate?
You can always add an overlay on the existing sharepoint calendar: http://office.microsoft.com/en-us/sharepoint-server-help/work-with-multiple-exchange-and-sharepoint-calendars-in-one-sharepoint-calendar-HA101777171.aspx
Maybe this is a solution
I have to admit though, I didn't get it to work. If I add an event in Outlook it doesn't get added to the SharePoint calendar. Some comments in the blog say it works though, give it a try. If you figure it out, please let me know.