Exchange Server 2007 Service Pack 1 Beta 2 is now available in beta for MSDN and Technet Plus subscribers, with a lot of improvements for the mobile devices. Look a the following list for a short overview:

• New Policies – A ton of new policies
• Bandwidth reductions – Less round trips and less data transferred.
• S/MIME support – S/MIME has been added and has backward support for WM 5 + MSFP.
• Sync State Upgrade for Migrations – Allows users to maintain their setting while their mailbox is transitioned from Exchange 2K3 to Exchange 2K7 (no need to re-sync to the new server).
• Default Policy Support – A default policy can now be set so administrators don't have to apply the policy to each user or write a script to iterate though users.
• Cancel Remote Wipe – Canceling remote device memory/storage wipes is available in OWA and though Exchange Management Console.

Check out a full list of the new features included in SP1 Beta 2, details.