Harold Wong has the news (lightly edited):
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 information about Windows Mobile based devices can be found here.
Details on the Windows Mobile 5.0 Messaging and Security Feature Pack are here.