Update Rollup 1 for Microsoft Exchange Server 2010

Microsoft has released Update Rollup 1 for Microsoft Exchange Server 2010 Release to Manufacturing . This article describes the following information about the update rollup:  http://support.microsoft.com/kb/976573

Important information for Outlook Web App users about Outlook Web App customization

When you apply an update rollup package, the update process overwrites the Microsoft Outlook Web App (OWA) files if it is necessary. If you have changed the Logon.aspx file or other OWA files, the customizations are overwritten to make sure that OWA is updated correctly. After you apply the update rollup package, you must re-create OWA customization in Logon.aspx.
We recommend that you always make a backup copy of any customized OWA files before you apply the update rollup

Note Make sure that you apply the update rollup to the internet-facing Client Access servers before you apply the update rollup to the non-Internet-facing Client Access servers.

For other Exchange Server 2010 configurations, the order in which you apply the update rollup to the servers is not important.