Typically hurricanes do not produce very much lightning. This is because vertical winds (updrafts) are limited to the eyewall and convective banding. Lightning is produced by electrification in which ice crystals are blown upward. In these updrafts friction redeposits the outer electrons in the crystals and redistributes the charges. Warmer temperatures and limited updrafts typically limit lightning in hurricanes.
This year hurricanes Emily, Katrina, and Rita seemed to break this general rule. Currently science seems to be lacking an explanation for this phenomenon. In the past hurricanes with a great deal of lightning have occurred during landfall when orography enhances upward motion. However, this year's hurricanes all experienced high electrification over the ocean where terrain was not an influence.
Check with NASA for more information.