Yesterday Microsoft has released Rollup 6 for Exchange 2007 SP1.
Update Rollup 6 for Exchange Server 2007 SP1 fixes the issues that are described in the following Microsoft Knowledge Base articles:
950675 Downloaded .xls file attachments are empty when you open the files by using Outlook Web Access on Exchange Server 2007 Service Pack 1
955443 Some free/busy messages are not replicated from Exchange 2007 to Exchange 2003 servers after some mailboxes are migrated from Exchange Server 2003 to Exchange Server 2007
956536 The Microsoft Exchange File Distribution service uses lots of memory and processor time when Exchange Server 2007 processes many OABs
956624 The Microsoft Exchange Transport service crashes continuously after you enable journal rule or deploy an antivirus application on an Exchange Server 2007 server
957748 The custom message class of contact object is overwritten by the normal IPM.Contact class when an Exchange 2007 server replicates the contact object to any other public store
959239 MS09-003: Vulnerabilities in Microsoft Exchange could allow remote code execution