Microsoft has released Update Rollup 1 for Exchange Server 2010 SP3. You can download it from here
Below are the some of the fixes included in Update Rollup.

1. Mailbox storage limit error when a delegate uses the manager's mailbox to send an email message in an Exchange Server 2010 environment
2. You cannot open a mailbox that is located in a different site by using Outlook Anywhere in an Exchange Server 2010 environment
3. Mailbox synchronization fails on an Exchange ActiveSync device in an Exchange Server 2010 environment
4. Rapid growth in transaction logs, CPU use, and memory consumption in Exchange Server 2010 when a user syncs a mailbox by using an iOS 6.1 or 6.1.1-based device
5. Unable to soft delete some messages after installing Exchange 2010 SP2 RU6 or SP3

Fifth issue was holding back lots of organization for SP3 upgrade.Update: 31|05|2013
List of issues that the update rollup resolves

Cheers,