The dates of the Steam Summer Sale for 2014 has apparently been leaked today. Those dates on which your wallet will be crying out in pain are June 19 - June 30, 2014.

Paysafecard, an electronic payment company, let the news slip earlier today with a promotional tie-in. This is in addition to the "Mysterious Cards" that were added to Steam about a day or so ago now. These Mysterious Cards can be earned right now by crafting badges for other games, though you cannot yet craft a badge with the Mysterious Cards just yet.