Greg : will you please do your recipe magic (and I guess piss a few more people off...) and block the iron duplication via railcraft?
The bug is this : Eloraam's alloy furnaces melt down vanilla iron containing items and give you the iron back. There is no configuration option to change how much iron you get back, nor to disable melting certain items.
Covert Jaguar's Railcraft allows you to make 2 minecarts using 5 steel, or up to 64 track using 6 iron. This means that when you melt down the minecarts or track, you get more iron than you started with.
Boom, infinite iron : and this affects IC2/Gregtech greatly because iron is usually the "governing resource" for playing Industrialcraft.
Both Covert Jaguar and Eloraam refuse to fix the problem or enable any sort of configuration option to fix it. (covert jag lets you disable the making of the minecarts, but it is off by defaut, but NOT the track recipes)
I have messaged them both in the Minecraft forums and they both say it's the other's fault.
Your crafty code could detect either or both and fix one of them. Virtually all hardcore players who enjoy your mod will be using railcraft and redpower.