These are some BB\RIM existing issues that were caused by SP2 RU4. Below are KB articles written with details around the issues and resolutions\workarounds.
Exchange 2010 SP2 RU4 Blackberry\RIM Issues
Email message delivery is delayed on a Blackberry mobile device after you install Update Rollup 4 for Exchange Server 2010 SP2
Declined meeting request is added back to your calendar after a delegate opens the request by using Outlook 2010
Duplicated email messages are displayed in the Sent Items folder in a EWS-based application that accesses an Exchange Server 2010 Mailbox server
ErrorServerBusy response code when you synchronize an EWS-based application to a mailbox in an Exchange Server 2010 environment