Operations Manager 2007 Targeting Series
Two good bits on targeting in Operations Manager 2007.
Part one is about the differences between MOM 2005 and Operations Manager 2007. http://blogs.technet.com/momteam/archive/2007/10/31/targeting-series-part-1-differences-between-2005-and-2007.aspx
Part two is about why targeting computers groups can fail in Operations Manager 2007. http://blogs.technet.com/momteam/archive/2007/11/14/targeting-series-part-2-why-targeting-a-computer-group-fails.aspx
Check out this site, they have gotten more active the past few months.