I'm running:
Craftbukkit 1.4.5 B 0.1
CommandHelper 2255 (latest)

I was trying to make sure sponges gave out no drops:

bind(block_break, array(id: sponge-break-id'), array(type: 19), @event,
       modify_event('drops', '')
        if(nequals(pmode(player()),'CREATIVE'),
                _notify_admins('break-rare-block', @event['block']['type'])
          )
   )

(where _notify_admins() is a simple script that tells the admins what happened)

The sponge did not drop an item entity of itself. In addition, hawkeye recorded the block broken as being "air" not sponge. In addition, a player was able to break the block despite not being a member of the Worldguard region the block was in.

So I did an experiment, and tried using the code to drop dirt blocks instead. I copied and altered the code found here:
http://wiki.sk89q.com/wiki/CommandHelper/Event_API/block_break
I found that the dirt blocks did not drop as expected.
That seems to be a problem with something I did- don't know what yet though. Ignore that bit

I'm gonna close this, since it's on redmine.