I think your question is a bit backwards. What features would a pulse need to indicate it was caused with intelligent intent? These pulses have plausible (although exotic) explanations as natural events. There are people who have looked at the bursts as possible signals (see: http://en.wikipedia.org/wiki/Search_for_extraterrestrial_int... ) but the more plausible explanation is natural.
So i guess that leads me to the next level of questioning. What known cosmic events need to be ruled out before intelligence behind the event gets on the list of probabilities, say somewhere in the top 20?
