Spotted by MSMobiles, the new release can be downloaded here.
The lowdown on the new version, courtesy of Microsoft themselves:
In summary, expect no major changes, but if you are having problems with ActiveSync, particularly with VPN scenarios, you may notice an improvement.
Microsoft ActiveSync 4.2 is the latest sync software release for Windows Mobile-based devices. ActiveSync provides a great synchronization experience with Windows«-based PCs and Microsoft Outlook right out of the box. ActiveSync acts as the gateway between your Windows-based PC and Windows Mobile-based device, enabling the transfer of Outlook information, Office documents, pictures, music, videos and applications to and from your device. In addition to synchronizing with a desktop PC, ActiveSync can synchronize directly with Microsoft Exchange Server 2003 so that you can keep your e-mail, calendar data, tasks and contact information updated wirelessly when you’re away from your PC.*
Changes in ActiveSync 4.2 help resolve connectivity related issues with Microsoft Outlook, proxies, partnerships, and connectivity.
* Microsoft Outlook Improvements: Resolves issues relating to error code 85010014.
* Proxy/DTPT interaction Improvements: Improved auto configuration of device Connection Manager settings when desktop has no proxy path to the internet.
* Improved Desktop Pass Thru behavior with ISA proxy failures.
* Partnership improvements: Better resolution of multiple devices with the same name syncing with the same desktop.
* Connectivity Improvements: Better handling of VPN clients (resolve unbinding of protocols from our RNDIS adapter). New auto detection of connectivity failure with user diagnostic alerts.
ActiveSync 4.2 supports PC sync via USB cable, Bluetooth, or infrared connection.