Digital Spy are saying the special is 90 minutes, I forget is this news?
The only official word we've had on length from the BBC is the Toy Fair poster in February, which was 60 minutes.
Due to the 3-D nature of the special and its post-production demands, I think 60 minutes is a credible length.
I imagine this could be a situation like "Journey's End" where it's written for a certain length, and if it goes over it goes over. It's not like the schedule in November is set in stone yet. If the special runs 75 minutes, the schedule can still accommodate that.