Second Tuesday of the month and yup, you've got patches to deploy. It's a pretty nasty month in patchville with real products getting exploited instead of the usual IE problems. This month it's Exchange on the chopping block:
Microsoft Exchange Server does not properly handle the vCal and iCal properties of email messages. Exploitation of this vulnerability may allow a remote, unauthenticated attacker to execute arbitrary code on an Exchange Server. (CVE-2006-0027)
Unauthenticated attacker to execute arbitrary code. Ouch. Check out the Microsoft Security Bulletin Summary for May 2006 and get to patching.