Exchange 2007 RU5 was released yesterday approximately 6 weeks after RU4 was released. The current release corrects numerous bugs with the complete list found athttp://support.microsoft.com/kb/941421. The roll-up does not require a reboot but may take a considerable amount of time to install so be prepared. In testing I have not encountered any issues installing the roll-up and unlike RU4 all services did start as expected. Expect to see the RU released via Microsoft Update the first half of December. Until then, you can download the update directly from Microsoft Download at http://www.microsoft.com/downloads/details.aspx?familyid=652ed33a-11a1-459c-8ffe-90b9cbfe7903&displaylang=en&tm.