Steam sales are always a huge hit, but they must come to and end at some point. That is no different for the this holiday sale except this time Valve wanted to make the magic last just that bit longer. The sale was due to end Jan 5th(tomorrow) but Steam have gone ahead and pushed for a encore weekend which will include all the most popular sales that have occurred over the holiday sale. So any deals you missed out on you may have second chance.
The encore weekend will end on Janurary 7th at 10pm PST, so make sure to get the games you really want for the price you prefer.