Microsoft has released the Update Rollup 7 for Exchange Server 2007 Service Pack 3 (KB2655203). Both 32bit and 64bit versions are now available to download at the Microsoft Download Center. You may see the details of fixes in this Rollup by reading the below MS KB article,
When you try to run the rollup, you may see the warning about certificate revocation list,this is because Exchange tries to connect to the certificate revocation list (CRL) that has been issued by the publisher of the update rollup package or of the service pack. please adjust the IE settings to workaround the warning shown before you proceed with the roll up installation.
You should revert the IE changes once you have finished with the installation of the rollup.
Also ensure that you disable the Forefront Protection for Exchange before the starting the installation and enable it back after the successful installation to avoid any potential issues.
According to MS, this rollup is going to be the final release under the standard support for Exchange 2007, see the statement from official Exchange team blog statement.
you will see a successful event after the clean upgrade of the product,
Windows Installer reconfigured the product. Product Name: Microsoft Exchange Server. Product Version: 188.8.131.52. Product Language: 1033. Reconfiguration success or error status: 0.
I did the upgrade on my LAB machine and the installation went so clean, and the services are running as expected.