It comes down to this.
Each raid will have a list. this list is based on a random roll,
When u want gear u can roll on it this moves u UP the list , this is called Suicide
When another member of the raid wants the Gear and he is lower in the list then you he will receive it
Upon receiving the gear he will be moved to the top of the list. This way everyone gets a chance on gear.
Its pretty much the same as a Need or Greed system only much more efficient and u can save ur suicide for drops u really want.
This will encourage players not to need on Minor upgrades and give room for overall improvement.
I hope i made sense
and lets test it out to see how well it works
here is the official wowwiki link if ur still confused
http://www.wowwiki.com/Suicide_Kings