Today's deal slashes Skyrim's price in half to $29.99, as well as taking 50 percent out of the Hearthfire and Dawnguard add-ons. However, at the time of writing Hearthfire is still at the regular 400 MSP, although Xbox spokestype Major Nelson indicates the price should lower later today, Dawnguard is rightfully half-off of 800 MSP.
Meanwhile Oblivion gets a 33-percent-sized chunk ripped out of it, that taking the previous Elder Scrolls game down to $9.99. There are discounts for its DLC too, with the Shivering Isles and Knights of the Nine add-ons half-price at 600 and 200 MSP respectively.
Update: The Hearthfire DLC is now at the indicated on-sale price of 200 MSP.