SharePoint 2010 comes with a revamped calendar list, you can now add up to 10 other calendars as overlay layer so the result is one calender view displaying data from several calendars:
When adding overlay calendar you can choose from two calendar types: SharePoint and Exchange.
And here is the catch. You can add Exchange calendar... but ONLY ONE... and ONLY YOURS! If you try to add another Exchange shared resources, you'll get either some weird permission errors or the calendar will be empty. Unfortunately this SharePoint feature is poorly documented so I raised Microsoft Support ticket and after more than one month I got my answer from Microsoft Specialist:
So why the hell there is the option to add Exchange calendar?
Anyway if you were trying to integrate SharePoint with Exchange, this is not a way. The only solution would be a custom development. Hope this will save your time.