As expected, the Summer Sale is now underway on Steam, or as they're calling this year's installment the Summer Picnic Sale. We can probably find more details when an announcement rolls in, but in the meantime, we can see that there are the usual discounts to be had, and this year's side game involves getting three free trading cards each day. Initial sales are for things like LEGO games for 30-75% off, the Arma franchise for 20-80% off, and the Call of Duty franchise for 50-67% off. Update: The announcement of this is now online:

The Steam Summer Sale has started! For the next 11 days*, take advantage of discounts on thousands of products, including games, videos, and software, as well as the exclusive Summer Picnic Sale trading cards.