We were also hit by the automatic update. (Exchange 2007)
We found all Exchange services were disabled. By checking another Exchange 2007 system we changed all matching services to Automatic and restarted. Now we have Exchange running but OWA is dead! Not a severe limitation (iow, we can get by for a short term albeit with some inconvenience to me personally!).
I tried to uninstall the rollup but it required the original Exchange 2007 CD which I couldn't find readily. In the meantime I will download another copy off Technet.
I've elected to do nothing further pending Microsoft giving me a reliable method of repair. From what I read in the blog - that degree e of reliability has not been reached yet.
Can I suggest to Scott, that the revised update install over the top of Rollup 4 and fix it automatically for us???