Moffat commented on the announcement saying " ‘It's about time. Technology has finally caught up with Doctor Who and your television is now bigger on the inside. A whole new dimension of adventure for the Doctor to explore.’"
This is not the first time the Whoniverse has touched upon three dimensions. The Children in Need charity special Dimensions in Time has touched upon it. As well as the Series 5's first teaser trailer (that can be seen in HD and 3D here.)
This news has already been criticised by many fans. Some saying "What's the point when barely any people have 3D TVs?". Others have wondered why they're going to be spending the money on 3D rather than trying to make it longer than one 60 minute special. Some are wondering whether it's going to be true 3D, or simply a 2D to 3D conversion.
My feeling is that this will be done in the same way as the Olympics. BBC One (HD) will both show 2D, while BBC HD picks it up in HD.
According to the Guardian (which means as far as we know right now, it's unconfirmed direct from a Beeb source), It's also been said that the 50th Anniversary will be making it's way into cinemas. The BBC's controlling of Drama commisioning has said: "We will be doing it on cinema screens as well. We are working out the logistics of that at the moment because we need to make sure the main BBC1 experience remains absolute value for money for the audience."
How will this go down? Only time will tell, but IMHO, 3D alone? Bad idea. Mix it with cinema releases in both 2D and 3D? Much better.
BBC Source. Guardian source.