Little flakey (running on Chrome Mac). I type in an answer, press Submit, and nothing happens. When I reload it finally updates and shows the next question.
Same here (even on Chrome Mac), but I get an "unknown error". But when I switch to coffeescript or ruby, it then shows up that I got the correct answer (in the Earn an Invite section).
Same, that only worked a couple of times for me though (Safari Mac)
I ended up making it all the way past the third question (though I had to enter the same solution a few times). I ended up getting the invite page but then just left.