Wizards have posted this announcement:

Wizards of the Coast
Thursday, January 07, 2010

As many of you have noticed, the DCI ratings have not been published since December 14. The ratings have been run each week, but the system that publishes the results is not currently functioning. We expect to have this problem solved early next week.

An additional issue is that the January 6 ratings are to be used to invite players to Pro Tour–San Diego.

When we publish the ratings the week of January 11, we will only include those events reported on and before January 4. We will use those published ratings to invite player to Pro Tour–San Diego. When we run and publish ratings the week of January 18, we will include all the events reported after January 5. Players that receive a ratings-based invitation to Pro Tour–San Diego will be contacted by email.

We appreciate your patience with this situation.
Update on DCI Ratings : Daily MTG : Magic: The Gathering