Just before you apply those update rollups to your Exchange 2007 servers....

I am sure you know by now if you have deployed a couple of Exchange 2007 Servers, that applying update rollups does not seem to be as easy as Next-Next-Next (haha promoting my blog my title). So just before you apply those update rollups for Exchange, you may want to take a look at the following articles.

Exchange Server 2007 managed code services do not start after you install an update rollup for Exchange Server 2007
http://support.microsoft.com/kb/944752

Managed code services does not start is usually because of the update rollups containing digital signatures which during the installation attempts to do a validation a certificate revocation list (CRL) at crl.microsoft.com/pki/crl/products/CSPCA.crl

So it is quite common for the organizations not to allow their Exchange Servers to go out to the Web and causing this validation during the installation of the rollup for the Exchange Services not to start.

A recommended fix out there is point crl.microsoft.com to 127.0.0.1 in the local hosts file of the servers before the upgrade. I can attest that this might work for some of the servers but in case it does not for all, you can still continue and modify your Exchange Services configuration file manually based on the article above.

For those who have Exchange 2007 servers in different server roles like CCR clustered mailbox servers, you can check the links below before you apply your rollup updates.

How to Install Update Rollups in a Single Copy Cluster
http://technet.microsoft.com/en-us/library/bb885045.aspx

How to Install Update Rollups in a CCR Environment
http://technet.microsoft.com/en-us/library/bb885047.aspx