An Calendar event seems to be locked when participants has accepted the invite using Exchange? I'm using the Calendar app in OS X Maverick to access my Office 365 hosted Exchange calendar. When I create an event with participants (be it people or rooms), the event title, location and participant list seems to be locked.

This only happens when a participant has accepted the invitation. I can still change the date and time, but an updated event isn't send the the participants.

I have tried to search for any documentation, that states this is limitation in the current synchronization methods between Calendar and Exchange, but to no avail.

Is something wrong in my setup or is this indeed a limitation in the synchronization between my Mac and Exchange?
This is a compatibility issue between Apple and Microsoft. There's not much you can do about that except using Outlook 2011 for Mac can help you out in this case.
As it is specific Microsoft software for Mac, you don't have all the limitations you have using the default (native) Mac Mail.app.

SideNote: A similar thing between Apple and Microsoft is when you flag an e-mail, it will be flagged as Outlook 2003, which is very pointless if your Exchange is 2007 or up.