Your companions will now show up as unique items in your Steam Inventory. Each one adds a bit of personality to your collection and may have special uses in the future. This update is the first step of the inventory system, and more surprises are on the way.
Your little buddies can now appear in your Steam Inventory.
Source: Steam Community (opens in a new tab)
Build and release context
Recorded Steam release date:
Within one calendar day of this post (UTC). The listed date does not establish an exact launch time.