As many of you are aware, the new Steam trading feature is out of beta and now officially live. It allows you to trade TF2 items with other Steam games or other items within Steam games (for now Portal 2 and Spiral Knights). Valve plans to add more games and inventories to this list and make this an ongoing feature for new games. Steam trading FAQ here.
Seeing the success of TF2 customization and item trading, this is one of those moments where everything is new and the possibilities are limitless. It could end with a fizzle as many seemingly great ideas do. Or it could be one of those must-have pieces that developers incorporate into their upcoming games. Some games will allow themselves to item trading such as role-playing games, while others like sports games may spawn their own new content as their trading currency. Perhaps an NFL game will have throwback jerseys, or a Premier League (that's soccer to all you scratching your heads) team will have fan chants...the possibilities are limitless.