Exchange Server 2003 SP2 has Released to Web as of today! To get your hands on this Service Pack, here's the link for the download: http://www.microsoft.com/exchange/downloads/2003/sp2/download.mspx. To learn more about Service Pack 2, please visit the SP2 site: http://www.microsoft.com/exchange/downloads/2003/sp2/overview.mspx.
In addition, Service Pack 2 offers a vastly improved experience in both managing and using mobile email. This comes with the tight integration with the Messaging and Security Feature Pack for Windows Mobile 5.0. The Mobile Operators will be releasing these new devices into the market over the next several months. More informatoin about Windows Mobile based devices can be found at http://www.microsoft.com/windowsmobile/business.
This is final code, but you should still test this in your lab environment prior to deploying in production.