There should be a a method to add item drops to vanilla blocks in forge so that your mod isnt incompatible with other mods that edits the same blocks, something like:

 

MinecraftForge.addItemDrop(Block, DroppedItem)

 

this would be really nice!

If such a thing were done, it would be best to pass in a callback, but regardless it is unlikely to be done (at least for 1.2.5).  There are too many inconsistent places that such things are placed, grabbed, overridden, etc...