Don Jones column this month is very useful started for BITS download automation. Read it here: Intelligent Transfer
I compiled some resources for anyone interested in going further. I have also added a link the teh Resouce Kit which containds the BitsAdmin Tool.
BITS Extensions: Remember that BITS can do uploads too. BITS is manageble via AD. BITS is fully accessible with dotNET and PowerShell.
BitsAdmin is here: Windows XP Service Pack 2 Support Tools
Scripting: <undocumented at Microsoft> <coming>