There are a few possible installation issues that we would like you to be aware of:
1. Exchange 2007 managed services might time out during certificate revocation checks
2. When installing a Rollup, we recommend you use the same account that you used to install Exchange Server. If you are using a different account, that account needs to have Local Administrator rights as well as rights to read Active Directory on Exchange object as well as server level (as the update needs to determine which roles are installed on the server). Not having required permissions can lead to OWA not being updated correctly and displaying a blank page after update has completed.
3. If you have modified the logon.aspx file, it will not be patched by the Update Rollup installer. As a result Outlook Web Access may not be updated correctly and it may display a blank page after the update has finished. In order to avoid this problem, rename the logon.aspx file before applying the update rollup. After you apply an update rollup package, you must re-create Outlook Web Access customization in logon.aspx.
If you have Cisco Unity and exchange server 2007, you might experience IP phone's LED (Voicemail indicator lamp) won't syncronize when a user receives or deletes a message. This update, kb952580, will fix the issue.
This update rollup 4 for exchange 2007 sp1 includes 951251 (http://support.microsoft.com/kb/951251/): A MAPI application does not work correctly if Exchange 2007 is installed on a Windows Server 2008 server.
More information on what was really broken, take a lok at http://blogs.msdn.com/stephen_griffin/archive/2008/07/03/mapi-download-and-the-enumprotocols-bug.aspx
Also If you are using Blackberry enterprise server 4.1.3 or later with exchange server 2007, you might want to update CDO&MAPI on BES, this is optional, here is an instruction
On this instruction remove ESM 2003, and follow the instruction in full.