The Exchange Server 2007 Autodiscover functionality must be enabled and configured by your system administrator. If you are upgrading from an earlier version of Mail for Exchange you will need to perform a full resync in order to take advantage of the new Contact field mapping (middle name, car phone, department, spouse and anniversary).
We're still waiting for full folder support in Nokia's Mail for Exchange. The application is in continual development so there's a good chance we'll see improved functionality in future versions. However if folder support is a feature your require you may wish to look at DataViz's RoadSync.
More information is available on the Nokia for Business website.