[Antivirus]

Lynne is correct - it sounds like what you're looking to do is much more complicated than you might think - I think your same objective could be reached by simply displaying a "featured forum" link in the navbar, or similar

however - if I were to do this, if you must actually move the forums around based upon a cron job, make sureto do so using the forum datamanager, as lots of other things are affected by changing the parentforumid for the forum you're moving, (such as cache entries, etc...) - simply updating parentforumid with a sql statement could prove disasterous for your forums.