Valve is giving developers the ability to create an in-game Steam Inventory system that is more efficient over the current means.
Presently, players are alerted to new inventory drops through notifications that appear in the top right bar of the client. For example, exiting a game could have a blinking indicator on top to tell you about trading cards that you’ve unlocked.
The new inventory features will allow players to put the items in their Steam inventory based on various factors.
“With this service, a game can easily drop items to customers based on playtime or can grant items based on specific situations or actions within the game,” says Valve. “These items can be marked as tradable through Steam or sellable via the Steam Marketplace. Developers can also configure recipes for crafting different combinations of items that result in more rare, unique, or valuable items.”
The Steam Inventory Service is currently in beta for Steamworks developers, and its use will vary from game-to-game as developers use it in different ways and with different kinds of content.