If you uncheck the OWA (Outlook Web) calendar option to
"Automatically place new meeting requests on my calendar, marked tentative"
The result will be that ALL calendar invitations come into the blackberry as text emails (no accept/decline options)
Since this is a user configurable option in OWA, you think RIM would have a technote on this. But all they have is this one: KB20866-Meeting invitations received from external domains show as regular email messages on the BlackBerry smartphone
Which is referring to external invites only and a different field.
I'm going to assume what we are experiencing with the "AddNewRequestsTentatively" value is also experienced by everyone else with Exchange/Blackberry environments.
If you have experiences one way or the other, please post.