There is nothing mentioned from Microsoft:http://technet.microsoft.com/en-us/l.../aa998911.aspx

That's exactly the document that I meant: There is stated the
following:

Deemphasized Functionality

There are legacy Exchange features that are now being deemphasized in
Exchange 2007:
Public folders - Free/busy calendaring functionality is provided by
the Availability service. If you need additional functionality,
migrate to SharePoint Portal Server or a similar product.
Proxy address generators - Use the Exchange Management Shell.
CDO 1.2.1 - This functionality is provided by the Exchange Web
Services.
MAPI32 - This functionality is provided by the Exchange Web Services.
CDOEX (CDO 3.0) - This functionality is provided by the Exchange Web
Services.
Exchange WebDAV extensions - This functionality is provided by the
Exchange Web Services.
ExOLEDB - This functionality is provided by the Exchange Web Services.
Store events - This functionality is provided by the Notification Web
service.
Streaming backup APIs.
Exchange 2003 Virus Scanning Application Programming Interface (VSAPI).