Developers with games on Steam can initiate sales without seeking approval from Valve now that new Steamworks tools have gone live. Promotions can be scheduled up to two months in advance and the discount percentage and sale promotion can also be customized.
It's worth mentioning that game discounts have a maximum run time of two weeks and promos for an individual title have to be spaced at least two months apart. Keeping that in mind, we're not likely to be flooded with Steam sales -- at least not any more than usual.
It's nice to see Valve give developers more autonomy. Sweet, delicious freedom.