Microsoft has released ActiveSync 4.2 as a Beta Preview. The new version promises to fix issues related to Microsoft Outlook synchronization and Desktop PassThrough. USB connectivity issues should also be resolved with this release.
I have not seen any information that indicates that there were any changes for WM2003 devices; all the changes appear to be focused on WM5.0. So, if you don’t want to lose the ability to synchronize over a network connection and are using WM2003, you should consider skipping this version as it does remove that functionality.
Note: Because this is a beta, the ActiveSync 4.2 Beta Preview should not be used on production systems in mission-critical environments.