so far none. before this device came out I always thought that this uses MfE and I can configure mac with google calendar and ical and use sync to sync with google contacts that way everything will be synced in cloud, but when this device came out and I used and tried to do it that way, kabam!!!! nope it did not work. apparently N900 and google do not want to sync through MfE.
Now only hope either nokia releasing an isync file for N900 or straighten up the MfE and google sync.