just wanted to point out that even though Rollup 3 (v3) supports UDP notifications now for Outlook 2003 on Exchange 2010 you still need to ENABLE it as follows:
Subkey location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeRPC\ParametersSystem
Subkey name: EnablePushNotifications
Note If this registry key does not exist, or if its value is set to 0, the UDP notification support feature is not enabled.
For more information please refer to the following support article:
Folders take a long time to update when an Exchange Server 2010 user uses Outlook 2003 in online mode
In addition Henrik provided additional information on UDP Push Notifications on his Wiki Article including how to set a fixed UDP port for these notification !