Don't see a thread on this yet...
According to this guy - http://i.imgur.com/7fR68.jpg
The steam autumn sale starts today, 21st November and runs until the 27th.
My wallet is upset already...
Updated:
Today's Deals - Ends in 48 Hours at 1pm EST 11/23
XCOM: Enemy Unknown - $33.49 | £20.09 (-33%)
Magic: The Gathering - Duels of the Planeswalkers 2013 - $4.99 | £3.49 (-50%)
The Walking Dead - $12.49 | £10.99 (50% Off) (UK/EU Buyers can buy at $12.49 from Amazon.com making it cheaper than the UK/EU price)
Darksiders II - $16.99 | £11.89 (-66%)
Age of Empires III Complete - $9.99 | £7.49 (-75%)
Terraria - $3.39 | £2.03 (-66%)