They should have just finished filming episode 14, so they're only about 2 episodes ahead of us. Besides the 8-10 days it takes to film each episode it also takes a couple of weeks for the post-production to be done.
This hiatus is because the show is taking 2 weeks off from filming for the holidays (starting today, btw). It's so Jensen & Jared and the entire cast & crew can take some much needed time off to rest, recharge, and spend time with their loved ones during Christmas & New Years. This is the one time they get any significant time off from filming outside of the long summer hiatus.
I think we can all agree that they deserve it for the long work days they put in nine months out of the year and for bringing us such an amazing show week after week. :D