Update: Version 1.1 of the 10.6.5 updater is online. If you're going with it, best to use the Combo updater.
If you were listening in on the Talkcast last night, you heard Steve relay a tale of woe from a client who rushed to update his server to the latest Snow Leopard build, 10.6.5, only to encounter a slew of Open Directory problems -- and with no backup to revert to safely. (Let it go forth from this time and place: Do Not Do This.)
Seems like his buddy may not have been alone in finding the update less than ideal: AppleInsider reports that the update has been "quietly pulled" from Apple's servers.
The problems with the update, as reported on Apple's discussion boards, include DNS resolution issues, LDAP/Open Directory master hiccups and remote storage/server connection drops. None of it good, and none of it immediately subject to workarounds; let's hope there's a patch to the patch sometime very soon.