Today, Steam officially launched their in-client trading system.
Steam Trading will allow Steam users to swap cross-game items with one another. Currently only Team Fortress 2 items, Spiral Knights items and gifts purchased on Steam can all be traded between one another, but it’s expected to expand across numerous games as more developers allow it.
The system works similarly to the systems used to gift Steam games and the Team Fortress 2 item trader.
Your Steam Community profile now has an item inventory that you can see what items you have eligible for trading.
This is a pretty cool feature, but I worry that developers will only really add tradeable items for their games through pre-ordering, rather than unlocking items within the actual game.