Apologies in advance if this is 'old hat', but Sky don't seem to have promoted this much... Following a recent software upgrade now means that you now don't have to subscribe to both Sports and Movies to view 3D
If you have Sky Sports HD, then you can now watch Sports on the 3D channel at no extra cost. (If you don't have the Movies, then any 3D films will continue to be blocked). If you have the entertainments package, then any Documentaries and Music shown on the 3D channel can be viewed also.
Just log into your Sky account on line (or via the i phone app) and follow the "Activate Sky 3D" links..