Ishaan from HackMIT here. Regarding interest, in the past week, we've gotten over 1500 signups –– more than we can handle, to be honest. But there's definitely no lack of interest.
For reference (orders of magnitude different, I know), I organized a local hackathon and heard from probably 100 'interested' people. We ended up netting 30 registrations, which was the cap for our venue, but I only actually turned 2 people away. So 2/3 of the developers that I spoke to and emailed personally couldn't make it, and that was in the city they already live in.