This by far is probably the most exciting change in May alongside the huge buffs and changes most exotics are getting.
Exotics will now have something similar to Legendary guns that will give people to chase (targeted to the hobbyists of Destiny).
First off every Exotic Weapon requires a 'Catalyst' to charge it. It will give you the information on how to do this, some maybe easy, one-off things, others longer and more cryptic.
Once charged it will give you a similar enhanced gun to Legendary Masterworks - generate orbs on double kills and kill counter.
The bit that will bring out a little more chase to find the info is that then there are further steps, or step for some guns that will give them a specific unique perk to add further dimensions to the gun. This bit is the one that makes me feel like its worthwhile coming back.
The perks added are unique to that Exotic. One speculated so far is the Vigilance Wing, the current beast of PvP, gets a Full Auto perk.
Finally they are making changes (and not far away either) to add what was missing in D2.