Today the Exchange Team released Rollup 2 for Exchange Server 2010 Service Pack 1 (KB2425179). This update raises Exchange 2010 version number to 14.1.270.1.
If your upgrading from Exchange 2007 you need to implement this rollup because the bug Exchange 2007 OWA redirect bug with Exchange 2010 sp1 is fixed check: kb2458419
The List with Fixes:
983186 The mailbox alias of a user contains the "?" character unexpectedly after you run the "Enable-Mailbox" cmdlet to create a mailbox for the user in an Exchange Server 2010 environment
2295902 An excepted occurrence is not excluded from a recurring iCalendar message for an Exchange Server 2010 mailbox user
2385017 You cannot edit public folder items even though you are the owner of the items in an Exchange Server 2010 environment
2385194 You cannot connect to an Exchange Server 2010 mailbox by using a MAPI application when a Mailbox server and a Client Access server are installed on different computers
2397171 You cannot reply or forward a large email message on an Exchange Server 2010 mailbox
2403783 An incorrect label is displayed in the date field in a public folder item when you open the item by using OWA in an Exchange Server 2010 environment
2408924 The subject of an item is deleted when you use the "UploadItems" operation together with the "Update" action or the "UpdateOrCreate" action in an Exchange Server 2010 environment
2409597 You cannot open a public folder item when the default public folder database for the mailbox database is unavailable in an Exchange Server 2010 environment
2423776 The Exchange Information Store service crashes frequently during a public folder replication process on an Exchange Server 2010 public folder
2431500 You cannot connect to an Exchange Server 2010 mailbox simultaneously by using Outlook Anywhere from several Windows XP-based computers
2433642 The "FETCH (BODYSTRUCTURE)" command returns a corrupted file name of an email message attachment on an Exchange Server 2010 computer
2452075 You cannot connect to mailboxes in a recovery database on a server after you install Exchange Server 2010 SP1
2458005 The Exchange Mailbox Replication service crashes when you use the "New-MailboxImportRequest" command to import a PST file to an Exchange Server 2010 mailbox
2458419 "A temporary change has occurred that requires you to connect to a different server" error message when Exchange Server 2007 mailbox users try to access their mailboxes by using an Exchange Server 2010 Client Access server
2322161 The replay queue length on passive copies of mailbox databases in Database Availability Group continues to increase in an Exchange Server 2010 environment
982004 Exchange Server 2010 users cannot access the public folder
983492 You cannot view updated content of an Exchange Server 2010 public folder
983549 Exchange Server 2010 removes the sender’s email address from the recipient list in a redirected email message
Download the Hotfix HERE