Looks like the work to upgrade Bungie.net and the new Seventh Column wasn't quite complete; the site is down again for maintenance at the moment. Stay tuned.

UPDATE: Looks like Bungie.net is back, perhaps this time for good. The new 7th Column site is also up, and if you check your profile page while logged in, the XBL integration also seems to be working again.

If you haven't linked your XBL Gamertag with your Bungie.net login by now, go and read the FAQ on Bungie.net about how to do it.