Strange. It seems to all be working at the moment, but we'll try to squash more of the bugs today--please feel free to email contact@javascriptbattle.com if you're continuing to see problems.
So - what happens is I get bounced through a few 302 redirects from github back to the page, but I remain not logged in. Then if I refresh the page it displays me as logged in then. Hope that helps. :)
I registered yesterday but today I can't login. The 'login with github' button doesn't do anything (just reloads the page).
Also the leaderboard seems to breakdown if you interact with it for a bit - just stops updating.