Update 17-11-2012: 2010 SP2 RU5 is currently not available due to an issue with the update.
Update 11-12-2012 2010 SP2 RU5v2 is now available. Details are here.
Exchange sustained engineering has released Exchange 2010 SP2 RU5 to the Microsoft Download Center.
The list of fixes is at the bottom of the post, though one worth mentioning is this: 2733415 Event ID 1 is logged on the Exchange Server 2010 Client Access server in a mixed Exchange Server 2010 and Exchange Server 2003 environment. If you have an Exchange environment with both Exchange 2003 & 2010, and you installed SP2 RU3 then you will be glad to see the flood of red in the application log can be stopped 
. SP2 RU3 introduced changes to RPC Client Access, and a side effect of this was Autodiscover and Exchange 2003 mailboxes. If a user had Outlook 2007/2010 installed and they ran Test Email Auto configuration then the following would be logged into the application event log:
Source: MSExchange Autodiscover
Event ID: 1
Task Category: Web
Level: Error
Description: Unhandled Exception "User setting 'PreferredSite' is not available."
And the net result can be a sea of red:
This occurs because the Exchange Server 2010 Client Access server does not calculate the PreferredSite value appropriately for the Autodiscover service request from the Exchange Server 2003 user.
Other notable fixes are:
2750293 Items remain in the "Recoverable ItemsDeletions" folder after the retention age limit is reached in an Exchange Server 2010 environment
2750847 An Exchange Server 2010 user unexpectedly uses a public folder server that is located far away or on a slow network
2743761 DAG loses quorum if a router or switch issue occurs in an Exchange Server 2010 environment
2748870 Declined meeting request is added back to your calendar after a delegate opens the request by using Outlook 2010
In addition to the above, Update Rollup 5 for Exchange Server 2010 SP2 resolves the issues that are described in the following Microsoft Knowledge Base (KB) articles:
- 2707146 IRM-protected messages cannot be returned in search results if the messages are recorded and sent to an external contact in an Exchange Server 2010 environment
- 2710975 Some MAPI property objects in an ANSI .pst file contain unreadable characters if you import the file by using the "New-MailboxImportRequest" cmdlet
- 2712001 ExTRA.exe does not collect data if you select a scheduled task for a data collection in an Exchange Server 2010 environment
- 2712595 Microsoft Exchange RPC Client Access service crashes when you run the New-MailboxExportRequest cmdlet in an Exchange Server 2010 environment
- 2716145 Store.exe crashes on an Exchange Server 2010 mailbox server if a VSAPI based antivirus software is used
- 2717522 Microsoft Exchange System Attendant service crashes on an Exchange Server 2010 server when you update the OAB that contains a DBCS address list
- 2720017 An RBAC role assignee can unexpectedly change a DAG that is outside the management role group scope in an Exchange Server 2010 environment
- 2727802 Microsoft Exchange Replication service crashes intermittently when you try to move mailboxes from an Exchange Server 2003 server to an Exchange Server 2010 server
- 2733415 Event ID 1 is logged on the Exchange Server 2010 Client Access server in a mixed Exchange Server 2010 and Exchange Server 2003 environment
- 2733609 Email message and NDR message are not delivered if an email message contains unsupported character sets in an Exchange Server 2010 environment
- 2743761 DAG loses quorum if a router or switch issue occurs in an Exchange Server 2010 environment
- 2748766 Retention policy information does not show "expiration suspended" in Outlook Web App when the mailbox is set to retention hold in an Exchange Server 2010 environment
- 2748767 You receive an NDR message that incorrectly contains recipients of successful message delivery in an Exchange Server 2010 environment
- 2748870 Declined meeting request is added back to your calendar after a delegate opens the request by using Outlook 2010
- 2748879 You cannot access a mailbox by using an EWS application in an Exchange Server 2010 environment
- 2749075 A copy of an archived item remains in the Recoverable Items folder of a primary mailbox in an Exchange Server 2010 environment
- 2749593 Outlook logging file lists all the accepted and internal relay domains in the Exchange Server 2010 organization when you enable troubleshooting logging
- 2750293 Items remain in the "Recoverable ItemsDeletions" folder after the retention age limit is reached in an Exchange Server 2010 environment
- 2750847 An Exchange Server 2010 user unexpectedly uses a public folder server that is located far away or on a slow network
- 2763886 "The operation failed" error in the Outlook client when you open a saved message from the Drafts folder and then try to send it in an Exchange Server 2010 environment
Cheers,
Rhoderick
