I have a piece of software that does uber monitoring on a server.  Using this tool I found out that during an Exchange 2007 the patch actually turns off the Exchange services and then disables them.

Then when the Exchange 2007 patching is finished it's turned back on.

Which now makes those early Exchange updates where they'd leave the services disabled after reboot understandable now.

So keep that in mind to doublecheck if you want to be a bit paranoid.  Go back in after the patch and ensure that the services are turned back on.