I marked this to blog about last week and they went "below the fold" in my e-mail and I didn't see them again until this morning. 

The Exchange 2003 update is important if you are running a mixed Exchange 2003/2007 environment.  And if you are using ISA 2006 with Exchange 2007 or planning to, the ISA update is important. 

Update for Exchange 2003 (KB 922817)

http://www.Microsoft.com/downloads/details.aspx?familyid=b217a4c9-4aad-49b9-92dd-10754af1029e&displaylang=en&tm

Overview

This update is required if the Offline Address Book (OAB) generation is moved from an Exchange 2007 server to an Exchange Server 2003 Service Pack 2 (SP2) server. It resolves issues which are caused due to changes in the OAB version 4 in Exchange 2007.
This update is also recommended if the OAB is generated on an Exchange Server 2003 SP2 server after Exchange 2007 is deployed in the Exchange organization.

Update for Publishing Microsoft® Exchange Server 2007 for Microsoft® Internet Security and Acceleration (ISA) Server 2006

http://www.microsoft.com/downloads/details.aspx?familyid=82b717ce-5b63-4098-8425-bbf4a5b7e09c&displaylang=en&tm

Overview

This ISA Server 2006 update adds support for publishing Exchange Server 2007 with ISA Server 2006.
Notes
• The Attachment Blocking option is no longer available when publishing Outlook Web Access for Exchange 2007. If you are using Exchange Server 2007, we recommend you configure attachment blocking on the Exchange 2007 server. For more information about configuring attachment blocking on Exchange Server 2007, see Exchange Server 2007 product Help.
• This hot fix also updates the ISA Server Management MMC snap-in.