I'm just coming back to D&D after being away since the end of AD&D 2nd Edition. I remember that monsters used to have a loot table that corresponded to a table in the DMG but I haven't seen or heard anything to indicate that's still the case.
How is treasue awarded in the new edition? I'm sure that a particular plot item can be inserted as the DM requires but what about random/wandering monster encounters?
The treasure tables will be in the DMG.
Thank you. 
Dungeon Master's Guide Treasure Tables
WotC's Greg Bilsland has shared some results from use of the DMG's random treasure tables!
- You receive seven malachite gems (50 gp each), a +1 shield, a wand of web, and bracers of archery.
- Twelve blue agates (50 gp ea.), Lantern of Revealing, Oil of Slipperiness, Potion of Hill Giant Strength.
- You receive disappointment. 12 gp, and 7 carnelians (50 gp each).
- HAHAH. I rolled a 1. No treasure for you!
- Your treasure hoard contains 7 lapis lazulis (50 gp ea), spell scroll (blur), potion of healing, potion of climbing, and 15 cp.
- Fortunately, you found a secret door and discovered another hoard, containing a silk robe, a silver necklace, and a tapestry.
- A beholder in its lair: You gain a headband of intellect, figurine of wondrous power (ebony fly), a cube of force, & a bunch of art (1750 gp total).
- A pony: 18 copper pieces in its abandoned saddle bag.