ActiveSync 4.5 Released
Just 2 days ago, Microsoft Launched the latest version of ActiveSync, ActiveSync 4.5 which could be downloaded at http://www.microsoft.com/windowsmobile/activesync/activesync45.mspx
However, if you're using Vista, then this does not apply to you.
Honestly, I've no idea what's the difference, except the newer UI. =)