I ran into an issue when working on a MOSS farm with the December update for MOSS.   Before applying the update,  I was running a basic x64 install with SP1.  The farm with MOSS had a one-way trust to a user-based domain.  The user-based domain didn’t trust the resource domain where MOSS was installed.   I needed to use the syntax of stsadm -o setproperty -pn peoplepicker-searchadforsts -pv “domain:example.com,Username,Password” as the article mentioned below since I had a one-way trust.

http://technet.microsoft.com/en-us/library/cc262051.aspx

This article also helped with the syntax.

http://blogs.msdn.com/joelo/archive/2007/03/08/cross-forest-multi-forest-configuration-additional-info.aspx

I strongly suggest you test this in a sandbox environment before applying or attempting to do your production environment. 

Hope this helps.