That has happened before and was being manipulated by bots. I suspect it is the same thing this time as that is quite a dramatic change from our usual download rate. I'm sure at some point the codeplex team will figure it out and put a stop the bots as they did before. For now I guess it may help real downloads by having that visibility on the codeplex home page but I'm sure its not legit, something must be doing some automated downloading to get the numbers that high. No way did we get 47K real downloads in one day that the chart is showing.
Wish it were true :-D
Best,
Joe