Eagle-eyed Steam users spotted a new article on the support page this morning, covering the service's coupon system. The catch? As far as anyone's aware, there's currently no such thing. Looks like someone let the cat out of the bag a touch early.
According to the article, the forthcoming system will allow you to attach one-use coupons to your account and redeem them for discounts on games when you're checking out. Apparently, some coupons will be limited to a subset of applicable games and come with expiration dates, but they'll also work on games that are already on sale unless otherwise noted.
Though it's far from confirmed, Blue's News is also reporting that the coupons will be tradable through Steam, allowing you to swap your discounts for full games or in-game items.
Even with this fairly conclusive (if accidental) announcement, there's still a lot we don't know about the coupons, including how and when you'll be able to get your hands on them. We expect to hear something official from Steam before the day is out, so stay tuned.