Valve has a horrid track record of concealing literally anything from anyone ever, so it really ought not to come as a surprise that the time and some details of the next steam sale have been revealed. Shacknews broke the story that an image had leaked out of a PayPal advertisement telling the public the date of the start of the sale.
We also know there will be no flash sales again, just as with the autumn sale just a few short months ago. I however think this is a good thing, as the sale is quite broken when everyone just waits for the lowest price. I actually wrote about that very thing recently and personally im quite all right with the new format.