I found this on mouse planet...
http://www.mouseplanet.com/10842/Disneyland_Resort_Update
Now, as you can see, there are many lengthly refurbs scheduled for the first few months of the year. After the Christmas season wraps up, the preparations for the 60th anniversary will be in full swing, and it will affect the whole half of the year (including the very busy spring break seasosn) ending mid-may just in time for the celebration.
Some of the rides are closing for simply a few days to do maintenance, while others are closing for months to do full-scale changes. For example, soarin' is getting a better screen projection and a sligtly different movie, perhaps to project images from all over the world, not just california. Matterhorn is getting a new bobsled track, as the recent additions have been really, really unpopular. And WOC is going dark for a couple months to get a few minor changes to the show. So after the refurbs let up, the rides should be in better condition, less likely to break down, and more enjoyable overall.