After successfully completing the last activity, this is the video you get:
It is quite interesting, for a couple reasons:
1) This helps us understand the comment Naomi made when she reached the Island in Season 3 – namely that Oceanic 815 (or what was thought to be it) was found
2) It is pretty clear at this point that the Maxwell Group is a function of Widmore and that some elaborate cover up was hatched
Overall, I think the ARG definitely helped make this last month go by much faster and hopefully we will continue to see more initiatives like this over the next 3 years.