Gravity uses LOTS of CG, I'd say it could easily qualify as an animated feature. Sometimes even the faces are CG, most of the time it's the real actors' faces with CG spacesuits, and in a few scenes you have real actors with real sets.
Slight SPOILERS follow!
CG is of course a great help in creating very long shots, you can put them together LEGO style from smaller sequences seamlessly. Although I do wonder about the rendering times for such loooong shots - even if renders for elements can be stopped whenever the object or character exits the camera view.
To integrate actors into CGI, they've build a 'lightbox' which is basically 6 walls of LED lights that can be programmed to display video sequences, to replicate the complete lighting environment. The actor/actress is then inserted to the middle and held by some sort of rigging and filmed with a motion controlled camera. This was mostly used for the scenes within the space stations where light had to come from all the environment. It was basically animated cubic environment mapping in real life
Also, they sometimes rigged multiple wires to the actors' limbs and people outside were literally puppeteering them.
Sometimes the rigging - including a bycicle seat - had to be painted out and as much as a complete leg had to be replaced with CG. The other big problem is that there's no greenscreen in the lightbox to create mattes for compositing in the CG backgrounds, so the actors have to be rotoscoped manually. It's also pretty stressful and requires a very good physique.
Another drawback was that the hair wasn't looking weightless. They cut Bullock's hair as short as they could but even that should've floated some more.
They can also make large movements by moving the camera instead of the actor, and changing the lighting environment to accomodate this movement. This is how they did the spinning - the camera was orbiting the actress. External shots usually had less complex lighting and only on the faces, so they were easier to do. They also didn't have to show the entire body, as all the spacesuits in those shots were CG as well.
All this pre-programmed camera movement and coreographed actor movement required the director to build pretty much the entire movie as a rough quality animatic, complete with frame-level timing and all. This is usually done for many action scenes, especially when lots of VFX work is involved, but here even simple events required LOTS of planning. I think only the Soyuz and the chinese capsule were actually built as real sets and the ISS and the chinese station were all CG.
The CG work is exceptionally good too, incredible details and some utterly amazing physics simulations for both simple zero G stuff and especially the large scale destruction. It does have a slightly stylized look compared to real-life space photography, but I believe lots of people would still have trouble guessing the real amount of CG work in the movie, despite the impossibility of most shots.
Now the really exciting question is indeed the one about how this type of filmmaking can be applied to other settings and genres? Cuarón has experimented with long takes augmented by CG to create a more immersive and less artificial feel in Children of Men, and it worked very well in that movie too. If the characters can just simply stand then some shots would be much easier to do with these motion controlled cameras and sometimes even the lightbox; but walking for example could prove to be problematic even if you don't see any feet.
Still, I believe that these techniques can and will be used, as the minimalist language is very effective and CG is advanced enough to support it in even more challenging ways. I'm already excited about whatever Cuarón is going to do next, even if it's certainly not going to take place in orbit
