All we have right now is the Travel Agents calendar. I have used it in the past and have no problems going by the times on this, as it is pretty spot on. I had to book my fireworks viewings and ADRs on this one as my window opened for ADRs last weekend.
http://www.disneytravelagents.com/S.../pdf/ParkHours/WDW_Operating_Calendar_Oct.pdf
Ordinarily I would wait for disney.com to release the official park hours on their site, but they seem to have a new way of doing it where you can only check them 10 days in advance from 180 days - which is a pain if you want to plan your days BEFORE you make your ADRs (I hate to state the obvious to Disney, but it's kind of the whole point

) I have no idea whether this was a temporary issue with the site or if they are implementing a new system for displaying hours

and to be honest, the last time I checked was a few days ago, but it was still the same then. As always, this could have changed and reverted back to the old method now. Worth a check first.