Bungie has knocked two major exploits on the head with Destiny Hot Fix 18.104.22.168, one related to the new item Three of Coins and the other to chest farming.
When Xur first arrived in the tower after The Taken King launched he brought with him a decidedly different set of wares than before. The biggest and most game changing difference was an item called Three of Coins, a consumable that increased the chances of Ultras (named enemies/bosses) dropping an exotic engram. With no cooldown and an additive chance to create a drop players quickly found ways to effectively farm exotic engrams. Whether it was the poor Fallen leader Draksis or the Vex Gate Lord, players collectively killed them over and over agaiun to farm those precious engrams. With 22.214.171.124 Bungie have introduced a background cooldown to lower the chance of an engram drop when rapidly killing Ultras.
The other major change was the adjustment of some chest spawn locations to prevent a cheesey method of farming them. Several quests/items require a crafting material called hadium flakes that are found exclusively on the Dreadnaught. Players learned that some chest spawns could be opened multiple times if a player left and re-entered instances quick enough.
A bug was introduced with this patch however that causes some Year 1 strike Ultras to drop no loot upon death. Bungie raced to fix the two exploits noted above so lets hope they show similar haste in fixing the strike bug. You can read the full notes on the hot fix here.