Trying to give something back to the Community...
I've installed WSUS on my Central Site and configured SUP to sync with Microsoft Update. All of the updates are coming down fine. Next I've installed WSUS on a Child Primary Site and configured the SUP.
However, no updates seems to be coming down from the Central Site (the "wsyncmgr.log" just sits there saying "Waiting xx minutes for requests…" and was last updated days ago).
[17/10/2012 - The WMUG Link Below No Longer Works - Please click HERE to access the Article]
Read the complete post at http://wmug.co.uk/blogs/cliffs_blog/archive/2010/09/21/faq-configmgr-2007-software-updates-not-being-synchronised-to-my-child-sites.aspx