Tim and Julie,
yes, <i>L. nasuta</i> is a sexually dimorphic species.
The difference is in the rostal protrusion. The males have a spiked protrusion (Jordans new snake is a male) and the females have a protrusion that looks alot like a leaf.
Also, males are usually brownish and females are sometimes more greenish in colour.
i did an undergrad thesis in snake sexual dimorphism...... personally, i think its one of the most facinating thing about snakes and the animal kingdom in general!